Class 9 Chemistry - Is Matter Around Us Pure

$$H_2O$$ contains hydrogen and oxygen but it is a pure substance. How?

A mixture is formed when two or more substances combine physically.

However, in $$H_2O$$, two hydrogen atoms combine with one oxygen atom chemically, forming a new substance that has properties different from hydrogen and oxygen.

Therefore $$H_2O$$ is not a mixture but a compound and it is pure.

What are the components of solution?

Solute and solvent are the components of solution.

Define a compound.

A compound is a chemical substance composed of identical molecules that are composed of atoms from more than one element held together by chemical bonds. For example, water is composed of molecules of $$H_2O$$. These molecules are identical and are composed of atoms of elements $$H \ and \ O$$.

Name the liquid which evaporates and then condenses during the process of distillation.

The liquid which evaporates and then condenses during the process of distillation is called distillate.

In the distillation process, the solution is heated, liquid component of the mixture evaporates in the form of vapours. These vapours are then condensed back into liquid form which is very pure and is called distillate.

Cloud is a colloidal suspension of water droplets in air.

If true then enter 1, else enter 0.

True (1). Clouds are colloidal solutions of condensed water vapour in air. They are aerosols in which dispersed phase is liquid (water) and dispersing medium is gas (air).

State two ways in which you can separate a mixture of sand and sugar.

Sand is not soluble in water, but sugar is soluble in water. So, the mixture can be dissolved in water. Sugar will form a solution with water and, sand will settle down. Sand can be filtered and separated, and sugar can be obtained by crystallization.

Smoke is an aerosol and a colloidal solution of carbon in air.
If true then enter 1, else enter 0.

Smoke is an aerosol and a colloidal solution of carbon in the air. in this colloidal solution dispersion phase is carbon, and the dispersion medium is air.

Two or more elements combine to form ...............

Two or more elements combine to form a compound. A compound is a substance formed when two or more chemical elements are chemically bonded together. Two types of chemical bonds common in compounds are covalent and ionic bonds. The elements combine together in a fixed ratio.

Table salt is made from sodium and chlorine which can be poisonous. Still we can eat table salt without getting poisoned. Why?

Table salt is sodium chloride, a compound which is different in properties from its constituent elements sodium and chlorine. Sodium is highly reactive element while chlorine is a reactive poisonous gas. But table salt made from sodium and chlorine is safe to consume.

How will you obtain $$NH_4Cl$$ from a mixture of $$NH_4Cl$$ and $$KCl$$?

$$\text{By Sublimation} $$

To separate a mixture that contains a volatile sublimable compound from a non-sublimable impurity or salt (like $$KCl$$) sublimation technique is used. $$NH_4Cl$$ is a volatile sublimable compound and $$KCl$$ is a salt.

By sublimation, $$NH_4Cl$$ sublimes leaving $$KCl$$ as residue.

"The properties of the product are different from those of the constituents". State whether this statement best describes an element, a compound or a mixture.

The given statement best describes about a compound having different property from those of its constituents.

What are pure substances? Give two example of pure substances.

A pure substance is made up of the same type of particles or atoms. All the elements and compounds are pure substances because they contain the same kind of particles.

Examples; Hydrogen, Carbon dioxide.

How will you separate a mixture of common salt, chalk powder and powdered camphor? Explain.

When this mixture is heated, Camphor shall $$sublime$$.
We can separate the mixture of common salt and chalk powder by putting the mixture in water. As we know that common salt is a homogenous mixture, so it will dissolve with the water and chalk powder is heterogenous so it could be separated by the filter paper

What are immiscible liquids?

$$Immiscible\; liquids$$: Liquid-liquid mixtures which do not mix and form true solutions, instead form a heterogeneous mixture called immiscible liquids. For example, oil and water are examples of immiscible liquids - one floats on top of the other.

A few mixtures are given above. Tabulate the methods to separate their components and give the reasons for selecting the method.

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How will you purify a liquid having non-volatile impurities?

Simple distillation will give us the pure liquid while the non-volatile impurities will remain in the flask as residue.

Suggest methods for the separation of the following mixtures.

A mixture of liquid $$A\ (b.p-365\,K)$$ and liquid $$B\ (b.p-356\,K).$$

A mixture of liquid $$A$$ and liquid $$B$$ can be separated by fractional distillation because the boiling points of the two liquids differ by just $$9^\circ C.$$

Classify the following substances into elements, compounds and mixtures:
(i) Milk (ii) 22-carat gold (iii) iodized table salt (iv) Diamond (v) Smoke (vi) Steel (vii) Brass (viii) Dry ice (ix) Mercury (x) Air (xi) Aerated drinks (xii) Glucose (xiii) Pertol/Diesel/Kerosene oil (xiv) Steam (xv) Cloud

Elements - (iv), (ix)
Compounds - (viii), (xii), (xiv), (xv)
Mixtures - (i), (ii), (iii), (v), (vi), (vii), (x), (xi), (xiii)

Suggest a method to purify camphor containing traces of common salt.

Camphor containing traces of common salt can be separated by sublimation. Camphor sublimes while common salt remains as a residue in the china dish.

A solution is prepared by dissolving certain amount of solute in 500 g of water. The percentage by mass of solute in solution is 2.38. Calculate mass of solute.

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A solution that has relatively less amount of solute with respect to the solvent is called a ________ solution.

Ans- $$Dilute$$

A solution that has a relatively less amount of solute in comparison to the solvent is called a dilute solution.

A solution that has a relatively more amount of solute in comparison to the solvent is called a concentrated solution.

Ammonium chloride can be separated from common salt by the method of ................

There are ways for separating mixtures of chloride salts such as that of sodium chloride and ammonium chloride. It can be done by crystallization, filtration, and sublimation. The easiest method among the three is separation by $$\text{sublimation.}$$ Ammonium chloride sublimes upon heating.

If true enter $$1$$, else enter $$0$$.
A standard solution is one whose concentration is not known.

Standard solution is a solution containing a precisely known concentration of an element or a substance. A known weight of solute is dissolved to make a specific volume. It is prepared using a standard substance such as a primary standard.

Why is air considered as a mixture?

Air is a mixture of various gases like nitrogen, oxygen, methane, nitrous oxide, etc. These gases retain their properties in air and hence the air is considered a mixture.

What do you mean by:
(a) Molecule of an element
(b) Molecule of a compound, with examples

(a) Group of atoms of same element is known as molecule of that element.

Example: $$H_2,O_2, N_2$$ etc.

(b) Group of atoms of different element is called molecule of a compound.

Example: $$CH_4, NH_3, CO_2$$ etc.

Can their be possibility of solid solutions?

A solid solution is a uniform mixture of substances in solid form. Example metal alloys like steel, an iron solvent with a carbon solute.

The major component of steel is ________.

Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost.

The major component of steel is iron.

Define heterogeneous mixtures and write its types.

Heterogeneous mixture: Combination of two or more pure substances in which chemical properties are retained.

They are of two types- Suspensions and colloids depending on particle size.

What is distillation?

Distillation is a method used to separate components of a mixture that boil without decomposition and have sufficient difference in their boiling point. In the mixture, the liquid having a lower boiling point boils first and is condensed and collected than the liquid having a higher boiling point.

Blood is an example of ________.

Blood has the characteristic of both a colloid and a suspension making it a colloidal suspension. In its normal stable state, blood is a suspension, which is a colloid.

So, we can say that blood is a colloidal solution.

Water is good solvent for ionic compounds.

Water has a high dielectric constant and is polar in nature therefore ionic compounds are soluble in water.

Give example of following type of Colloid.
Emulsion

$$\textbf{Examples of emulsions are:-}$$

(i) Egg yolk

(ii) Butter

(iii) Mayonnaise

$$\bullet$$ An emulsion is a type of colloid formed by combining two liquids that normally don't mix.

$$\bullet$$ In an emulsion, one liquid contains a dispersion of the other liquid.

$$\bullet$$ The process of mixing liquids to form an emulsion is called emulsification.

Give example of following type of Colloid.
Solid sol

$$\textbf{Examples of solid sol are:-}$$

(i) Alloys

(ii) Coloured glasses

(iii) Gemstones

$$\bullet$$ In this colloidal solution, both dispersion medium and dispersed phase are in the solid state.

Give example of following type of Colloid.
Gel

$$\textbf{Examples of gel are:-}$$

(i) Curd

(ii) Cheese

(iii) Shoe polish

$$\bullet$$ Gel are the type of colloidal solution in which the dispersed phase is in its liquids state whereas the dispersed medium is in its solid state.

The process of settling of sand, when a mixture of sand and water is left undisturbed for some time is known as ______________.

Sedimentation is the process of allowing particles in suspension in water to settle out of the suspension under the effect of gravity. The particles that settle out from the suspension become sediment. Settling of sand particles when a mixture of sand and water is left undisturbed for some time is known as sedimentation.

Suggest a suitable method to separate the components of the mixture of two volatile components with an appreciable difference in boiling points.

$$\text{Distillation}$$

This method is used for the separation of a mixture containing two miscible liquids that boil without decomposing and have a large difference between their boiling points. The process of conversion of a liquid into vapor by boiling and then recondensing the vapor into liquid is called distillation. In this method, a liquid that has a lower boiling point will evaporate first at constant temperature and after condensation can be collected in another vessel in this way we can separate a mixture of volatile liquids.

Under which category of mixtures will you classify alloys and why?

Alloys are homogeneous mixtures. They are made of a mixture of different elements (mostly metals) that are mixed uniformly.

________ (Matter/Atom) can be classified chemically into pure substances and mixtures.

Matter can be classified in many ways. Matter can be broken down into two categories: pure substances and mixtures.

Pure substances are further broken down into elements and compounds. A pure substance is composed of one type of atom or molecule.

Mixtures are physically combined structures that can be separated into their original components.

Therefore, the correct answer is "Matter".

A mixture of iodine and sand are separated by method of _______ . (filtration/sublimation)

The mixture of iodine and sand can be separated by the process of sublimation. When heated, Iodine undergoes sublimation i.e changes directly from solid to gas but sand will not sublime.

So, the correct answer is sublimation.

A mixture of oil and water can be separated by using ______ (separating/filtration) funnel.

Answer: A mixture of oil and water can be separated by using $$\underline {separating}$$ funnel.

A separating funnel can be used to separate the components of the mixture of immiscible liquids. Oil and water are two immiscible liquids and form two different layers in separating funnel.

How is 'chromatography' applied in the separation of coloured constituents present in a mixture of ink?

Simple chromatography is carried out using a strip of filter paper. A spot of the dye is placed near the bottom of the paper and the paper is then placed upright in a suitable solvent, e.g. water. The ink is soluble in water. As the water rises on the filter paper it takes along with it the dye particles. Usually, a dye is a mixture of two or more colours. The coloured component that is more soluble in water, rises faster and in this way the colours get separated.

Define crystallization.

Crystallization is also a chemical solid-liquid separation technique in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.

What would you observe when crystals of copper (II) sulphate and iron (II) sulphate are separately heated in two test tubes?

Copper(II) sulphate crystals in pentahydrate form is blue in color which on heating in the test tube loses water molecules forming gray-white powder.

On heating, iron(II) sulphate loses its water of crystallization and the original green crystals are converted to brown colored anhydrous solid.

Explain the method of crystallization.

Crystallisation is a method used to remove impurities from solids. In this method, the solid to be purified is dissolved in water and then filtered to remove impurities. The solution is heated such that water evaporates to get a saturated solution. Later, as it cools, the pure solid crystallises out in pure form. Purification of salt and alum are examples of solids that are purified using this method.

Blood is a _________.
true solution
colloid
suspension
(Give your answer using respective number)

Blood is a colloid. It has blood cells, nutrients, minerals, etc. which are the dispersed phase, and the dispersing medium is plasma (containing water and other dissolved components).

Water is purified for scientific purposes by distillation. Describe the process.

It is a process used to separate a pure liquid from a mixture of liquid.
The process of distillation begins with heating a liquid to boiling point. The liquid evaporates, forming a vapour.
The vapour is then cooled, usually by passing it through pipes or tubes at a lower temperature.
The cooled vapour then condenses, forming a distillate. The distillate is a purified form of the original liquid.
When the liquid evaporates, many impurities are left behind, so they are not present in the distillate.

Why is water called an universal solvent?

Water is called the universal solvent because it is capable of dissolving more substances than any other liquid. Water is a polar covalent molecule in which the hydrogen atom has a positive charge, whereas oxygen has a negative charge. When water comes in contact with any substance, it breaks the electrostatic force holding the molecule. As a result, many substances get dissolved in water.

Explain the following giving examples.
$$(a)$$ Saturated solution
$$(b)$$ Pure substance
$$(c)$$ Colloid
$$(d)$$ Suspension

(a) The term saturated solution is used in chemistry to define a solution in which no more solvent can be dissolved. It is understood that saturation of the solution has been achieved when any additional substance that is added results in a solid precipitate.

Example: Saltwater

(b) Pure substance: A material that is composed of only one type of particle.

Example: Gold, oxygen and water

(c) Colloid: A homogeneous non-crystalline substance consisting of large molecules or ultramicroscopic particles of one substance dispersed through a second substance.

Example: Gels, sols and emulsions

d) Suspension: A suspension is a heterogeneous mixture in which solute-like particles settle out of a solvent-like phase sometime after their introduction. We apply the word suspension when particles are big enough to eventually settle.

Example: Wheat flour and water, muddy water

Classify each of the following as a homogeneous or heterogeneous mixture:
Soda water, wood, air, soil, vinegar, filtered tea.

A homogeneous mixture has uniform composition and appearance.

A heterogeneous mixture consists of visibly different phases or substances.

From the list of given substances:

Homogeneous mixtures are soda water, air, vinegar, and filtered tea.

Heterogeneous mixtures are wood and soil.

Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.

$$Explanation:$$

We take water as a $$solvent$$ to make tea. We add tea powder, milk and sugar as a $$solute$$ to water to make tea.

Heat this $$solution$$ to $$dissolve$$ the solutes in water.

After heating, we can see that sugar and milk are $$soluble$$ in water but tea powder is $$insoluble$$ Therefore, filter the tea to separate out tea powder $$residue$$ from tea.

The $$filtrate$$ is our tea.

Which of the following materials fall in the category of a pure substance?
$$(a)$$ Ice
$$(b)$$ Milk
$$(c)$$ Iron
$$(d)$$ Hydrochloric acid
$$(e)$$ Calcium oxide
$$(f)$$ Mercury
$$(g)$$ Brick
$$(h)$$ Wood
$$(i)$$ Air

Pure substances are defined as substances that are made of only one type of atom or molecule.

The pure substances are:

(a) Ice

(d) Hydrochloric acid

(e) Calcium oxide

(f) Mercury

Identify the solutions among the following mixtures.
$$(a)$$ Soil
$$(b)$$ Seawater
$$(c)$$ Air
$$(d)$$ Coal
$$(e)$$ Soda water

A solution is a homogeneous mixture of two or more substances.
Out of the above mixtures, seawater, air, and soda water are solutions.

What is the difference between distillation and fractional distillation?

The simple distillation process is used to separate a mixture of liquids having greater difference in their boiling points (greater than 25 K). On the other hand, fractional distillation is used to separate liquids from a mixture with very less difference in their boiling point (less than 25 K).

In simple distillation, the apparatus consists of a distillation flask connected to a condenser. On the other hand, the apparatus used for fractional distillation is similar to that of simple distillation, but an additional fractionating column is fitted between the condenser and the distillation flask.

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True or False.
The properties of compounds are the same as those of the constituent elements.

False, A compound's properties are different from that of its constituent elements. For example, water is made up of oxygen, a gas and hydrogen which is also a gas, whereas water, a compound formed by oxygen and hydrogen, is a liquid.

Which of the following is likely to be a pure substance?
A) A colourless liquid that boils over the range 70$$^o$$C to 80$$^o$$C.
B) A green solid which starts to melt to 80$$^o$$C and is completely melted at 90$$^o$$C.
C) A white solid which produces a chromatogram consisting of only one spot.
D) A brown liquid that is completely miscible with water.

A substance is called a pure substance if and only if it has a fixed melting point and boiling point.

(A)Liquid has boiling point in range $$70-80^oc$$.So,no fixed point -not pure.

(B)The melting point varies from $$80-90^oc$$.so,not pure.

(C)Chromatogram gives only one spot-Pure substance.

(D)Brown liquid has some water in it.-impure.

State True or False.
Distilled water cannot be separated into its constituents by physical methods.

Since compounds are formed as a result of chemical change, they cannot be separated into its constituents by physical means. Energy in the form of light, heat, or electricity is required to separate them

Is air considered a solution? Explain.

Yes, air is a solution.

A solution is a homogeneous mixture of two or more substances. Air is an example of a solution (gaseous solution) because it is a homogeneous mixture of different gases like oxygen, nitrogen, helium, hydrogen, etc.

Match the examples with suitable separation process:

(A) If the boiling points of two liquids are not the same, they are separated by $$fractional\ distillation$$ method.

Eg: $$petroleum$$.

(B) Some liquids decompose when heated to their boiling points by $$vacuum\ distillation$$.

Eg: $$glycerol$$.

Steam distillation of various $$aromatic\ herbs\ and\ flowers$$ can result in two products; essential oil and a watery herbal distillate.

Hence, $$A-3, B-1, C-2$$ is correct.

Distinguish between true solution and colloidal solution.

1) A true solution is homogeneous in nature whereas a colloidal solution is heterogeneous.

2) The particle size of the solvent of true solution is less than 1 nm whereas in a colloidal solution it ranges between 1 nm to 1000 nm.

3) The particles of the true solution are not visible even under ultra microscope wheresas in case of colloidal solution, they are visible.

4) A true solution does not show tyndall effect whereas a colloidal solution shows.

State differences between aerosol and foam?

Aerosol	Foam
Disperse phase is either liquid or solid.	Disperse phase is gas.
The dispersion medium is gas.	The dispersion medium is liquid or solid
Examples: Fog, mist, clouds, smoke	Examples: Whipped cream, shaving cream, foam on beer.

Can we separate the compounds of an azeotropic mixture by fractional distillation? Explain

We cannot separate the compounds of the azeotropic mixture by fractional distillation. Because azeotrope is a constant boiling mixture. When an azeotropic mixture is boiled, the composition of vapor is the same as that of an unboiled mixture.

In centrifuge how are particles of different densities separated?

The centrifuge works using the sedimentation principle, where the centripetal acceleration causes denser substances to move outward in the radial direction. At the same time, objects that are less dense are displaced and move to the center.

Differentiate true solution and colloidal solution.

$${\text{True Solution}}$$	$${\text{Colloidal solution}}$$
1. Homogeneous	1. Heterogeneous
2. Solute exists as a molecule or iron	2. Solute exist aggregate of $$100-1000$$ molecules
3. Exert high osmotic pressure	3. Exert low osmotic pressure
4. Solute size $$<1nm$$ called Amicrons.	4. Solute size $$<1-100nm$$ called sub microns.

Colloidal solution of solid in liquid is called ________.

A colloidal solution is classified on the basis of dispersion phase and dispersion medium.
Here, the dispersion phase is $$Solid$$ and the dispersion medium is $$liquid$$, so the colloidal solution is called $$Sol$$.

Note: $$Sol$$ should not be confused with $$Solid\ Sol$$ which has dispersion phase as $$Solid$$ and the dispersion medium is also $$Solid$$.

What type of colloid is formed when a gas is dispersed in a liquid? Give an example.

When gas is dispersed in a liquid, the type of colloid formed is foam.

Examples: shaving cream and whipped cream

Answer in one word or one sentence.

Ornamental gold-containing copper is an example of what type of solution?

Ornamental gold-containing copper is an example of a solid solution. In this case, both solute and solvent are solids.

How will you separate oil and water from their mixture?

Oil, being lighter than water, will float on it. Two distinct layers are formed and slowly oil is allowed to flow into another container and is separated from the water. Separating funnel can also be used to separate the two.
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How much copper sulphate will be required to saturate 100 g of a dilute aqueous solution of $$CuSO_4$$ at $$25^oC$$ if 10 g of the dilute solution leave on evaporation and drying 1.2 g of anhydrous $$CuSO_4$$ in water at $$25^oC$$ is 25.

100 g of dilute solution of $$CuSO_4$$ contain
$$=1.2\times 10=12.0 g \,CuSO_4$$
Mass of water present in dilute solution
$$=(100-12)=88 g$$
To saturate 100 g of water, $$CuSO_4$$ required $$= 25 g$$
So, to saturate 88 g of water, $$CuSO_4$$ required $$=\dfrac{25}{100}\times 88 = 22 g$$
Thus, the mass of $$CuSO_4$$ to be added to 100 g of dilute solution to saturate it $$=(22-12) = 10 g.$$

Define the following terms:
(i) Solution
(ii) Solute

Solution is formed when minor component gets totally mixed with major components, the minor components are called solute and major components are solvent.

What is meant by a pure substance? Give examples.

The substances that are free from any kind of mixture and contain only one kind of particle are pure substances.

Examples of pure substances are iron, aluminum, silver, and gold.

State the properties of solution.

Properties of a solution:-

(1) A solution is a homogeneous mixture.

(2) Particles of a solution are smaller than $$1nm(10^{-9}\ meter)$$ in diameter. So, they can't be seen by naked eye.

(3) Because of very small particle size, they do not scatter a beam of light passing through the solution. So the path of light is not visible in the solution.

(4) The solute particles cannot be separated from the mixture by the process of filtration. The solute particles do not settle down when left undisturbed. That is, a solution is stable.

Define elements, compounds and molecules.

Element: An element is a substance that is made entirely of one type of atom.

Example : the element zinc is made up of only zinc atoms.

Molecules: Molecules are a group of atoms covalently bonded to each other.

Molecule can consist of atoms of the same element, or atoms of different elements. e.g. $$H_2$$

Compound: A compound is a substance that is made up of two or more different elements that are chemically joined, such as $$NH_3$$.

Give a reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several meters away.

a) Naphthalene balls disappear with time without leaving any solid, because naphthalene balls sublime and directly changes into vapour state without leaving any solid.

(c) We can get the smell of perfume sitting several meters away because perfume contain volatile solvent and diffuse faster and can reach people sitting several meters away.

Name the method you will use to separate two immiscible liquids.

The separation of two Immiscible liquids is done using a separating funnel. The above figure shows a separating funnel clamped to a stand. In this case, the mixture to be separated contains oil and water.
Immiscible liquids do not mix well and have different densities. When the mixture is left undisturbed, the denser liquid comes to the bottom of the funnel, and the lighter liquid stays on top of it. Now by operating a stopcock carefully, one can transfer the denser liquid (here, water) to the conical flask. The stopcock is closed when water is completely transferred from the tunnel. The separation is done multiple times to ensure the complete separation of the two components. Oil remains in the funnel and water is separated in a conical flask.

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What do you observe on the filter paper on which a drop of ink is placed, and as the water rises on it?

As the water rises on the filter paper, it takes the more soluble colors with it to the top and less soluble colors are carried up at a slower pace. We can see different coloured spots on the filter paper after the separation.

Give two examples of homogeneous mixture.

Homogeneous mixture-

A homogeneous mixture is a solid, liquid, or gaseous mixture that has the same proportions of its components throughout any given sample.

Example-

[1] Tap water

[2] Air

Differentiate between homogeneous and heterogeneous mixtures with examples.

The difference between heterogeneous and homogeneous mixture is the degree to which the materials are mixed together and the uniformity of their composition

example of:

homogeneous is blood plasma.

heterogeneous is sand in water.

In one sample of brass, the following components were found: Copper $$(70\%)$$ and zinc $$(30\%)$$. Identify the solvent, solute, and solution from these.

Solution = Copper+zinc = Brass

Solvent = Copper ( as it is $$70\%$$ part of solution),

Solute = Zinc (as it is $$30\%$$ part of solution).

Answer in one word/ a few words.

A pure substance formed when atoms or molecules of different elements combine.

A pure substance is a chemical substance that is composed of a particular set of molecules or ions that are chemically bonded.

Example:

Two molecules of hydrogen combined with one molecule of oxygen to form water.

$$2{ H }_{ 2 }+{ O }_{ 2 }\longrightarrow 2{ H }_{ 2 }O$$

What kind of mixture is gunpowder?

Gunpowder is actually a homogeneous mixture consisting of 70% $$KN{ O }_{ 3 },$$ 15% of charcoal and 10% of sulfer.

How are sol, solution and suspension different from each other?

Hint: Sol, solution and suspension can be easily differ on the basis of their physical properties.

All these three can be understand by following differences :

Define the term 'compound'?

A compound is a substance that results from a combination of two or more different chemical elements, in such a way that the atoms of the different elements are held together by chemical bonds that are difficult to break. These bonds form as a result of the sharing or exchange of electrons among the atoms. The smallest unbreakable unit of a compound is called a molecule.

Answer in one word/ a few words
The simplest form of a pure substance made up of only one kind of atom -_______________.

The simplest form of substance made up of only one kind of atom is called an element.

What do you mean by Solution, Solvent, Solute and Concentration.

Solution:-It is the homogeneous mixture of two or more chemically non reacting substance which has the same composition throughout the solution. e.g $$NaCl + {H_2}O$$

Solvent:-The part of the solution which is present in a larger amount and contains solute.

Solute:-The part of the solution which has a low amount by mars.
It is present in Solvent.

Concentration:-It means the amount of solute present in solvent as a solution.

Explain the meaning of the term matter with special reference to the term 'substance'.

The term matter means anything that has mass and occupies space, and which can be felt by the senses. A substance is a form of matter having the constant chemical composition and characteristic properties.

Answer in one word/ a few words.
A homogeneous mixture of solvent and solute.

A homogeneous mixture of solvent and solute is called a solution.

A solute is a substance that to be dissolved.

The solvent is the one present in excess and it dissolves the solute.

What is fractional distillation? Explain.

Fractional distillation is the separation of a mixture into its component parts. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize.

Name a kind of substance that is a combination of different elements.

The combination of elements gives a substance that is called a compound.

For example,

Water is made up of hydrogen and oxygen.

The mass of $$10\%$$ glucose solution is $$200\ g$$. Find the masses of the solute and the solvent used to prepare the solution.

Mass percent $$=\dfrac { mass\quad of\quad solute }{ mass\quad of\quad solution } $$

Give mass of solution $$=200gm$$

Mass of solute $$=x$$

Mass percent $$=10$$

$$\therefore$$ $$10$$% $$=\dfrac { x }{ 200 } $$

$$\therefore$$ $$x=20gm\Rightarrow $$ Mass of solute $$x=20gm$$.

We know that mass of solution $$=$$ mass of solute $$+$$ mass of solvent

mass of solvent $$=200-20=180gm$$

What is meant by a substance?

Hint: A Substance has uniform composition and has some mass.

Explanation of answer:

A substance is a form of matter which has definite properties and composition.

Every pure compound and element around us is a substance.

Examples: Common salt $$[NaCl]$$, Sugar etc.

Give a brief description of crystallization with an illustration.

Crystallization $$\rightarrow$$ The process by which a pure substance is separated from its solution in the form of crystals is known as crystallisation.

The impure substance is dissolved in a suitable solvent in which it is sparingly soluble at room temperature. The solution is concentrated by heating to get nearly a saturated solution. When this saturated solution is cooled, crystals of the pure substance will separate out.

Example: Crystallization of potash alum

Potash alum (phitkari) is highly soluble in water. The commercial sample is shaken with water when alum dissolves. The insoluble impurities are removed by filtration. The solution is then heated and then cooled. On cooling, pure crystals of alum separate. The soluble impurities are left behind.

Write one example of heterogeneous mixture used in daily life situations.

Examples of heterogeneous mixtures in daily life is oil and water mixture. Milk is also an example of heterogeneous mixture.

Why is milk regarded as a mixture and not as a pure substance?

Pure substances are either elements or compounds while the mixture is a resultant product of any two or more substances.

Milk consists of fatty acids, proteins, minerals. So it is a colloidal mixture.

Write three difference between colloidal solution, solution and suspension.

	Solutions	Suspensions	Colloids
Appearance	Clear Transparent Homogeneous	Cloudy Heterogeneous	Cloudy but Uniform & Heterogeneous
Particle Size	Molecule in size	Larger than $$10,000\overset {o}A$$	$$10-1000\overset {o}A$$
Tyndall effect	None	Variable	Light is dispersed

What is the principle of fractional distillation?

Fractional distillation is used to separate a mixture of two or more miscible liquids which boil without decomposition and for which the difference in boiling points is less than 25K.

Ex: Fractional distillation of crude oil

Differenciate beetween Homogeneous and heterogeneous mixture with example :

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When the stopper of a bottle containing colorless solution was removed, the bottle gave out a smell like that of vinegar. Identify the solution. What is the nature of the solution?

The solution is of acetic acid which is acidic in nature.

List any two properties of a colloid.

$$\text{Properties of a Colloid are-}$$

Colloid is a heterogeneous mixture of a dispersed phase and a dispersion medium but due to small particle size, it appears as a homogeneous mixture to naked eye.
Particle size varies from 1 to 100 nm (nanometer).
Particles of a colloid pass through filter paper, which means that they can not be separated by filtration.
Colloids are stable, that is, their particles don't settle down when left undisturbed for some time.

Which type of mixtures are separated using distillation method? If the difference in boiling points of constituents is less than $$25K$$ then which method will you adopt? Give an example where this method is used for separation.

Mixture which have components having difference in boiling point usually more than $$30^oC$$ are separated using distillation method.

If the difference in boiling points of constituents is less than $$25 K$$ then fractional distillation method is used for separation of it's component. Fractional distillation method is useful for separating ethanol from a mixture of ethanol and water.

List out the items in your house which comes under pure substances and mixtures ?

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Define a pure substance. How many types of pure substance do you know?

Any substance that is made up of single type of particles that have same chemical nature. For example water, sugar, salt, sodium, tin etc.

i) Elements - examples are iron, silver, gold mercury etc.

ii) Compounds - examples are water, carbon dioxide, methane, vinegar etc.

Two volatile and miscible liquids can be separated by fractional distillation into pure component', is true under what conditions?

1326430_1319155_ans_dd8b0f9b68374b1194d84ede30da611d.jpg

Write the steps you would use for making tea. Use the words, solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.

Hint: Tea is a solution of solute tea leaf and solute sugar and solvent milk.

Explanation:

1. At first take 100 ml of water as a solvent.

2. Boil it for a few minutes.

3. Now add solutes one teaspoon sugar and one teaspoon tea leaves.

4. Boil it for some time and solute sugar will easily mix with the solution then add some amount of solvent milk.

5. Now boil it for a few minutes so that sugar will get dissolve in water.

6. Now filter it through a filtrate in a cup.

7. The insoluble tea leaves will be left behind as residue.

What is solute?

A substance that is dissolved in a solution is called a solute. In fluid solutions, the amount of solvent present is greater than the amount of solute. One of the best examples of solute in our day to day activity is salt. Salt dissolves in water and therefore, salt is the solute.

Tyndall effect is exhibited by ________.

The Tyndall effect is the phenomenon in which the particles in a colloid scatter the beams of light that are directed at them. This effect is exhibited by all colloidal solutions and some very fine suspensions.

Therefore, the answer is colloidal solutions.

Write the difference between molecule and compound.

A molecule is formed when two or more similar or different atoms combine. For example, $$H_2$$ and $$CO_2$$ are molecules.

A compound is formed when two or more than two different atoms combine. In a compound, the molecule is the smallest unit.

For example, $$NaOH$$

State three reasons why do you think air is a mixture and water is a compound?

Air is a mixture because:

1. It contains two or more pure substances.

2. By physical processes, it can be separated into a simpler substance.

3. Its composition is not fixed.

Water is a compound because:

1. Its composition is fixed and inseparable.

2. It has a definite formula and is present in a proportion by mass.

What is major difference between a solution and an ordinary mixture ?

Mixture consist of two or more constituents in any proportion which is either distinct or indistinct whereas solution are homogenous mixture which is completely mixed and can be separated.

What are the two types of pure substances? Give one example of each type.

Pure substances are classified into two categories:

a) $$\text{Element}$$ b) $$\text{compound}$$

An $$\text{element}$$ is homogeneous in nature made up of only one kind of atom. For example, iron and silver are made of only iron and silver atoms.

A pure substance, basically composed of two or more elements and chemically combined in a fixed proportion is called a $$\text{compound}$$. Therefore, water is a compound. It has two elements, hydrogen and oxygen, combined in a fixed ratio.

Name one element, one compound and one mixture.

Sulphur is an element, water is a compound and air is a mixture.

Which of the following are 'Pure substances'?
Ice, Milk, Iron, Hydrochloric acid, Calcium oxide, Mercury, Brick, Wood, Air

A pure substance has a fixed chemical composition throughout.

Ice, Iron, Hydrochloric acid, Calcium oxide, and Mercury are pure substances because their chemical compositions are the same throughout.

List five characteristics by which compounds can be distinguished from mixtures.

(i) Compounds are pure substances while mixtures are impure substances.

(ii) Compounds cannot be separated by physical process while mixtures can be separated.

(iii) Compounds show different properties from their constituents while mixtures retain the properties of their constituents.

(iv) Compounds have fixed composition while mixtures have variable composition.

(v) Compounds have fixed melting or boiling points while mixtures don't have fixed melting or boiling points.

Choose the solution form among the following mixtures:
Soil, Sea-water, Air, Coal, Soda-water

Solutions are the homogeneous mixture of solute and solvent.

Here solutions are sea-water and soda-water remaining are mixtures.

State two reasons for supporting that brass is a mixture and not a compound.

Brass is a mixture because:

1. It does not have a fixed composition.

2. It shows the properties of its constituents.

Which of the following are not compounds?

Chlorine gas, Potassium chloride, Iron powder, Iron Sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond

Chlorine gas, Aluminium foil, Iodine vapour, Graphite, Sulphur powder, Diamond are not classified as compounds.

Give two reasons supporting that water is a compound and not a mixture.

Water is a compound because:

It cannot be separated into its constituent elements by physical methods.
The property of water is completely different from its constituent elements hydrogen and oxygen.

Define a compound. Give two points of evidence to show that sodium chloride is a compound .

A chemical compound is a substance made up of two or more elements combined together chemically in a fixed proportion by mass.

Sodium chloride is a compound because:

1. It consists of two elements sodium and chlorine and the product formed from these is different from the constituent elements.

2. It has a fixed proportion of constituents by mass.

Draw a labelled diagram showing fractional distillation.

Fractional distillation is the process used to separate a mixture of miscible liquids whose boiling points differ by less than $$25^oC$$. The experimental setup is similar to that of distillation except for a fractionating column which is filled with glass beads.

In this method, the mixture is heated using a burner, and both the liquids most likely enter the vapour state. The vapours hit the glass beads in the column and tend to condense. Out of the two vapours. the vapour component which is less volatile cools faster than the other and returns to liquid state. Gradually. the more volatile component reaches the top of the column and is passed through the condenser as shown in the figure and gets liquefied.

The less volatile component remains in the round bottom flask. The process is repeatedly done to completely separate the two liquids.

1623649_1773043_ans_00d47b3598554b8fad9f335f1ae6df8a.png

Give two characteristics each of:
(a) Pure substances
(b) Mixtures

(a) Pure substances:

A pure substance is a type of matter which is made up of a single type of particles. The constituent particles are identical in their chemical nature.
The constituent particles of a particular pure substance will always be in a fixed composition and cannot be separated using physical methods. Elements and compounds are examples of pure substances.

(b) Mixtures:

They are a type of matter formed by more than one pure substance. The constituent particles are just mixed together In different proportions to give different mixtures.
The properties exhibited by the mixture are the same as the properties exhibited by the individual constituent particles. These constituents can be fairly separated using physical techniques. Sugar solution, milk, are examples of mixtures.

Is ink a pure substance or mixture? Give reason.

A pure substance is made of constituent particles that are the same in their chemical composition whereas mixtures consist of two or more substances.

Thus, ink is a mixture since it is made of two substances i.e. water (solute) and dye (solvent).

Identify colloid from the following mixtures:
Muddy water, sugar in water, ink, blood, soda water, foam

Ink, blood, and foam are examples of colloids.

Name the two components of a colloid.

The components of a colloidal solution are the dispersed phase and the dispersion medium.

Explain the following giving examples:
(a) Saturated solution
(b) Unsaturated solution
(c) Suspension.

(a) A solution in which at a given temperature, no more solute can be dissolved by the solvent is called a saturated solution. The concentration of such solutions is the maximum at a given temperature. For example: If we mix salt in water to get a salt solution, and continue adding the salt slowly while stirring. At some point of time, the solution reaches a state where even though salt is added and stirred, some of the salt stays undissolved. The solution has reached its saturation level at that temperature.

(b) A solution in which at a given temperature, more solute can be dissolved by the solvent is called an unsaturated solution. Unsaturated solutions can be made saturated by adding more solute to it. In the activity mentioned in (a), the solution obtained in the beginning (before salt started remaining undissolved) is an unsaturated solution.

(c) A suspension is a heterogeneous mixture of 2 or more components. The particles forming the suspension are visible to the naked eye. In this mixture, the solute particles do not dissolve in the solvent. Instead, they remain suspended in the solvent medium. When left undisturbed, the solute particles tend to settle down at the bottom of the container. For example, a mixture of sand and water forms a suspension.

How will you separate a mixture containing benzene and diesel (difference in their boiling points is more than $$50^oC$$), which are miscible with each other?

A mixture of 2 miscible squids whose boiling points differ by more than $$50^o$$ can be separated using a technique called distillation. The liquids must not decompose upon boiling.
The mixture of liquids is taken in a round bottom flask and is heated. The liquid component with a lower boiling point starts to escape from the mixture and the gas is passed through a condenser. The cold water helps to condensed the gas into its liquid form and is collected in a beaker.
In the given mixture, at around $$60^oC$$. benzene gets converted into a gaseous state and is sent through the condenser to get benzene back in the liquid state.
Finally, diesel remains in the round bottom flask and benzene in the beaker.
1633637_1773027_ans_955e30f04d614d359a3b50be4bf4b2e4.png

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Define (a) solute (b) solvent.

(a) The solute Is the component that gets dissolved in a solvent to form a solution. It Is present In a smaller amount when compared to the solvent.

(b) The solvent is the component that dissolves a solute to form a solution. The solvent Is present In larger amount when compared to the solute.

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Fractional distillation method is used for the separation of different gases from air. Why is it so?

To separate the different gases from air, they are to be liquened first to implement fractional distillation. The air is cooled and compressed to obtain liquid air. One can see that the boiling points (b.p.) of various constituents differ by less than $$25^oC$$.
For instance. the b.p. of oxygen is $$-183^o C$$ whereas the b.p. of nitrogen is $$-196^o C$$. So simple distillation would convert both Into gaseous state, and one would fall to separate them. Due to this reason, fractional distillation is used.
In this case, both liquids get converted into vapour state and passes through the fractionating column. The less volatile component gets condensed and becomes a liquid again. The more volatile component suffers less condensation. As a result, the more volatile component tends to reach the top of the fractionating column. This vapour at the top Is condensed and coltected In a beaker.
For the separation to be effective, this process is done multiple times.

Define solution.

A solution is a homogenous mixture of 2 or more substances.

The substance present In the larger amount (solvent) dissolves the substance present In the smaller amount (solute).
Example:

1633526_1772999_ans_4fd154baa0a049dcb9673d13149fd9fe.png

Show diagrammatically, how will you separate two immiscible liquids?

1637863_1773046_ans_6b12ba9b53364e608401db213f8c1762.png

When blue ink is heated, what do you think has got evaporated from the watch glass ?

On heating the blue ink which is a mixture of water (volatile) and dye (non-volatile), the solvent water got evaporated from the watch glass leaving the solute, dye. The process involved is evaporation of water.

Give an example of solution containing a solid solute in a solid solvent.

Alloys like copper in gold is an example of solution containing a solid solute in a solid solvent.

State the basic difference between simple and fractional distillation.

Simple Distillation	Fractional Distillation
It is used for the separation of components of a mixture having significant differences(more than $$25 K$$) in their boiling points.	Used to separate a mixture of two or more miscible liquids which have a less than $$25\, K$$ of difference in their boiling point.

Write one property of colloids.

Colloids are stable heterogeneous mixture that does not settle down when left undistributed. Colloidal particles are too small to be visible to the naked eye but are large enough to scatter a beam of light that passes through it and makes the path visible, phenomenon known as Tyndall effect.

Give one example of the following:
Aerosol

Aerosol : Fog

Fog is an aerosol which has liquid as the dispersed phase and gas as the dispersing medium.

You are provided with soda water, milk, and muddy water. How can you differentiate between them in terms of:
(i) Homogeneity
(ii) Filtration
(iii)Tyndall effect

Soda water is a homogeneous solution and as such it can be differentiated based on the property of homogeneity.

Muddy water is a heterogeneous mixture and can be separated by filtration.

Milk is a colloid and exhibits the property of the Tyndall effect.

Give one example of the following:
Solution

Solution: Lemonade water

In lemonade water, the sugar and the salt are evenly distributed giving rise to a homogeneous mixture of the same.

Suggest separation technique(s) one would need to employ to separate Mercury and water.

We can use a separating funnel to separate mercury and water.

Mercury and water are immiscible liquids. Mercury is denser than water will settle down in the separating funnel and water being lighter will form a layer above it making it easier for them to be separated.

A mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of and the lower layer will be that of .

A mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of water and the lower layer will be that of chloroform. It is because the density of water is less than that of chloroform.

Which of the tubes in the figure will be more effective as a condenser in the distillation apparatus?

Tube (a) will be more affective as a condenser in the distillation apparatus. Presence of pores increases the surface area that comes in contact with the vapours. This allows more time for condensation of vapours and hence the first column would be more effective than the second column without marbles.

Suggest a suitable method to separate the components of a mixture containing two or more coloured constituents soluble in some solvent.

The mixture of coloured constituents can be separated by chromatography.

This method of separation is based on the fact that though two substances dissolved in the same solvent can have different solubilities. The component which is more soluble rises faster on a filter paper and gets separated from the less soluble component.

Suggest separation technique(s) one would need to employ to separate Kerosene oil, water and salt.

We'll be using more than one method of separation for separating the following mixture.
To separate kerosene oil from the saltwater solution we'll make use of the separating funnel as they are immiscible liquids.
The saltwater solution can then be easily separated by using boiling as water's boiling point lower than that of salt.

Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures: A volatile and a non-volatile component.

Ammonium chloride and sodium chloride.

The mixture can be separated by sublimation of ammonium chloride.

Give an example of a mixture having two volatile components with an appreciable difference in boiling points. Suggest a suitable method to separate the components of this mixture.

Acetone and water. The boiling point of acetone is $$56^{\circ}C$$ and the boiling point of water is $$100^{\circ}C$$. The difference in boiling points is $$44^{\circ}C$$. The mixture can be separated by evaporation or simple distillation as the difference in boiling point is more than $$25^{\circ}C$$.

Give an example of a mixture containing two immiscible liquids. Suggest a suitable method to separate the components of this mixture.

Two immiscible liquids are kerosene and water. Their mixture can be easily separated by using a separating funnel.

What would you observe when an aqueous sugar solution is heated to dryness?

When the aqueous sugar solution is heated, the water will initially evaporate. When the solution is heated to dryness, the sugar will get charred.

Give two examples for each of the following :
(a) Metals
(b) Non-metals
(c) Metalloids
(d) Noble gases

(a) Metals : Iron, silver, gold.
(b) Non-metals : Carbon, sulphur, oxygen.
(c) Metalloids : Antimony, silicon, boron.
(d) Noble gases : Helium, argon, neon.

State the information obtained from the formula of a compound.

$$\textbf{Explanation:}$$
The formula of a compound gives the following information:
1. Types of elements present in the compound.
2. Number of each kind of atom in one molecule of the compound.
3. Mass of one molecule of the compound.

Example:

$$\bullet$$ A molecule of carbon dioxide gas is represented by $$CO_2$$ .
$$\bullet$$ It indicates that a carbon dioxide molecule is formed by the combination of two elements i.e. carbon and oxygen.
$$\bullet$$ "Each molecule of carbon-dioxide is formed from one atom of Carbon and $$2$$ atoms of Oxygen.
$$\bullet$$ The mass of one molecule of carbon dioxide can be calculated by adding the mass of one atom of carbon and two atoms of oxygen.

Name two compounds which dissolve in water.

Two compounds which dissolve in water are $$\text{sugar, table salt}$$.

A solution is always a liquid. Comment.

No, a solution is not always a liquid. Solid solutions and gaseous solutions are also possible. E.g. Brass is a solid solution. Air is a gaseous solution.

A mixture of two or more miscible liquids, for which the difference in the boiling points is less than $$25 K$$ can be separated by the process called ________.

Fractional distillation is used for the separation of a mixture of two or more miscible liquids for which the difference in boiling points is less than $$25K$$.

FIll in the blanks
A metal which is a liquid at room temperature is __________.

A metal which is a liquid at room temperature is $$\underline{\textbf{mercury(Hg)}}$$.

Fractional distillation is suitable for separation of miscible liquids with a boiling point difference of about $$25 K$$ or less. Explain how it improves the efficiency of distillation.

A fractionating column makes the process of fractional distillation more efficient than the process of simple distillation by providing increased possibilities for condensation of the liquid. A fractionating column packed with glass beads or glass helices provides a large surface area for the vapours to collide and lose energy so that they can be condensed and distilled quickly. Increasing the length of the fractionating column would also increase the efficiency of fractional distillation.
1651358_1791569_ans_1b333252e40c4605b99bab3932e4f884.png

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A child wanted to separate the mixture of dyes constituting a sample of ink. He marked a line by the ink on the filter paper and placed the filter paper in a glass containing water as shown in the figure. The filter paper was removed when the water moved near the top of the filter paper. What would you expect to see, if the ink contains three different coloured components?

If the ink contains three different coloured components, three different bands will be seen on the filter paper.

Define a pure substance. How many types of pure substances do you know?

Pure substances: "A substance of a definite composition which has consistent properties and the only one type of molecule throughout, is called a pure substance".
Pure substances are of two types (i) Elements. (ii) Compounds.

State four important characteristics of compounds.

$$\textbf{Explanation:}$$ Important characteristics of compounds.
1. A compound has properties entirely different from the properties of its constituents.
2. Components of a compound are present in a definite proportion.
3. A compound is made up of one or more atoms of the same or different elements.
4. It cannot be separated into its constituents by simple physical means.

Write the molecular formulae of compounds calcium oxide, hydrogen sulphide, carbon monoxide and lead sulphide.

Molecular formulae of the given compounds are as below
Calcium oxide = CaO
Hydrogen sulphide = $$H_2S$$
Carbon monoxide = CO
Lead sulphide = PbS

State two characteristics of water which prove that it is a compound.

1. Elements in a compound are present in a definite proportion.

2 atoms of hydrogen combine with 1 atom of oxygen to give 1 molecule of water.

$$H_2 + O \rightarrow H_2O$$ (water)

So, it is a compound.

2. Compounds have a definite set of properties.

The properties of the compound water are different from the properties of the elements hydrogen and oxygen in the water.

(a) Why do sugar and water retain their individual properties in a sugar solution?

(b) Why do petrol and water form a heterogeneous mixture?

(c) Why sulphur does dissolve when carbon disulphide is added to a mixture of iron and sulphur but not when it is added to iron sulfide?

(a) As sugar solution is a mixture and mixtures has not any specific set of properties. They show the properties of the individual components from which they are formed.

(b) Petrol and water forms a heterogeneous mixture as their constituents can be seen separately and are not uniformly distributed throughout their volume.

(c) Sulphur has the property to dissolve in carbon disulphide whereas iron does not dissolve and retains its individual property. However, On heating Iron and Sulphur, they chemically combined forming Iron Sulphide. In this, Iron and Sulphur particles do not exist separately as such they lose their individual property.

Define the following:
(a) Pure substance
(b) Impure substance

(a) A pure substance is either an element or compound. It contains the same kind of atoms or molecules and has a definite set of physical and chemical properties.

Example of pure substance is oxygen gas, made of oxygen molecules $$O_2$$.

(b) A substance in which some other substances are also present in smaller or larger amounts is called an impure substance. Mixtures are impure substances.

An example of an impure substance is air. It is a mixture of several gases like oxygen gas, hydrogen gas, nitrogen gas, etc.

From the list given below select the correct substance which is most suitable for the statements given: (oxygen, diamond, zinc, graphite, gold)
A metal that is brittle.
Which non-metal is a good conductor of electricity?
The hardest naturally occurring substance.
The most ductile metal.
A gaseous non-metal.

The most suitable choices for the above statements are given below:

(1) Zinc
(2) Graphite
(3) Diamond

(4) Gold
(5) Oxygen

Select homogeneous and heterogeneous mixtures from the following:

The salt solution, petrol and water, sand and charcoal, alcohol and water, air dissolved in water, air, seawater, fruit juices, mist, brass.

A homogeneous mixture is a solid, liquid, or gaseous mixture that has the same proportions of its components throughout any given sample.

Homogeneous mixture: Salt solution, alcohol and water, air dissolved in water, air, seawater, brass.

A heterogeneous mixture has components in which proportions vary throughout the sample.

Heterogeneous mixture: Sand and charcoal, fruit juice, mist, petrol and water.

Which of the following options is correct for the given statement:
All pure substances have
the same physical state
the same colour
the same composition
a definite set of properties

The correct option is (4).

All pure substances have a definite set of properties but they can vary in their physical states, chemical compositions and color.

Complete the statement - an element is a pure substance made up of (identical/different) atoms.

An element is a pure substance made up of $$\textbf{identical}$$ atoms.

Examples: Carbon, Hydrogen

Classify substances into pure and impure substances in the form of a chart or tabulation.

1664977_1798632_ans_945d7601325d4c74bb53900ae25f28c1.PNG

Select the correct answer from the choice in brackets.
A compound [nitrogen / ozone/ zinc chloride]

A chemical compound is a chemical substance composed of many identical molecules composed of $$\textbf{atoms from more than one element}$$ held together by chemical bonds. Two atoms of the same element bonded in a molecule $$\textbf{do not}$$ form a chemical compound, since this would require two different elements.

Nitrogen $$N_2$$
Ozone $$O_3$$
Zinc Chloride $$ZnCl_2$$

Hence the answer is $$\underline{Zinc\; Chloride}$$

Why do we need pure substances?

We need pure substances because of the following reasons:
1. A pure substance has a fixed melting and fixed boiling point.
2. A pure substance has its characteristic taste, colour and odour.
3. Pure substances can not be broken further into more simple substances by any physical means.

State the technique involved in separating the following:
(a) Iodine crystals and potassium chloride
(b) Iron and chalk powder
(c) Potassium chloride from an aqueous solution of potassium chloride
(d) Rice powder from soil particles
(e) Iron filings from sand
(f) Large diamonds from very small diamonds

(a) Iodine crystals and potassium chloride: Sublimation (iodine is sublimable)

(b) Iron and chalk powder: Magnetic separation (iron is magnetic)

(d) Rice powder from soil particles: Sieving (rice particles are larger than soil particles)

(e) Iron filings from sand: Magnetic separation (iron is magnetic)

(f) Large diamonds from very small diamonds: Sieving (large diamonds will be retained in the seive)

The process of separation of liquid from solid, by removing the liquid layer at the top from the layer of settled solid below is known as ___________.

Decantation is the process of separation of liquid from solid and other immiscible (non-mixing) liquids, by removing the liquid layer at the top from the layer of solid or liquid below. The process can be carried out by tilting the mixture for pouring out the top layer.

Define: Miscible liquids

Miscible liquids: Homogeneous liquid-liquid mixtures are called miscible liquids. Examples of miscible solutions include water and organic compounds such as alcohols.

Define solvent.

A solvent is a medium in which a solute dissolves. It is in large quantity In a solution. Water is the most common solvent. Examples of other solvents include alcohol, carbon tetrachloride, etc.

____________ is a process to obtain a very pure form of a solid dissolved in a liquid.

$$Crystallization$$ is a process that separates a pure solid in the form of its crystals from a solution.

and _ are pure substances.

Elements and compounds are both examples of pure substances.

A substance that cannot be broken down into chemically simpler components is an element.

A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into their elements, or a combination of the two.

The correct answer is elements and compounds.

Define solute.

Solute: A solute is a substance that dissolves in a medium which can be water or any other substance. The solute is in smaller quantity in a solution.

How is distillation more advantageous than evaporation?

The advantage of $$distillation$$ is that both components of the solid and liquid mixture are obtained whereas in $$evaporation$$ only solid is obtained.

A pure substance has definite __ and constant _ .

Pure substances are defined as substances that are made of only one type of atom or molecule. The purity of a substance is the measure of the extent to which a given substance is pure.

A pure substance has definite $$composition$$ and constant $$properties$$ {$$Answer$$}

A ________ substance has only one kind of matter.

Answer: A $$\underline {pure}$$ substance has only one kind of matter.

When we speak of a $$pure$$ substance, we are speaking of something that contains only one kind of matter. This can either be one single element or one single compound, but every sample of this substance that you examine must contain exactly the same matter with a fixed, definite set of properties.

The method used to separate miscible liquids that vary greatly in their boiling points is _______.

The method used to separate miscible liquids that vary greatly in their boiling points is $$\underline{simple\ distillation}$$. For example, a mixture of acetone (boiling point: 329.2 K) and water (boiling point: 373.2 K) can be separated by this method.

An _________ is a homogeneous mixture of two or more metals.

An $$alloy$$ is a homogeneous mixture of two or more metals.

Examples : Steel, Brass.

The composition and properties of a __________ mixture is uniform throughout.

The composition and properties of a homogeneous mixture are uniform throughout.

A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.

Chalk powder dissolved in water is an example of a __________.

A suspension is a heterogeneous mixture containing large particles that will settle on standing. Sand in water and chalk powder dissolved in water are examples of suspensions.

On dissolving chalk powder in water, it does not dissolve completely. The chalk powder settles down which can be seen with naked eyes.

Fill in the blanks:
A _________ is a uniform mixture of a solute and a solvent.

A solution is a homogeneous mixture consisting of a solute dissolved into a solvent. The solute is the substance that is being dissolved, while the solvent is the dissolving medium.

The answer is "Solution".

Immiscible liquids are separated by using a _________.

A $$separating \;funnel$$ is a piece of laboratory glassware used in liquid-liquid extractions to separate the components of a mixture into two immiscible solvent phases of different densities.

Differentiate between solution and suspension.

$$\begin{array}{|c|c|}\hline \text { Solution } & \text { Suspension } \\\hline 1 . \text { It is an example of homogeneous mixture. } & 1 \text { . It is an example of heterogeneous mixture. } \\\hline \text { 2. It is formed when a solid dissolves in liquid. } & \text { 2. It is formed when an insoluble solid is added to solvent. } \\\hline \text { 3. For example - sugar dissolved in water. } & \text { 3. For example-chalk dissolved in water } \\\hline\end{array}$$

Name the liquid or medium of dissolution which allows the solute to dissolve in it.

The liquid or medium of dissolution which allows the solute to dissolve in it is called a solvent. The most common solvent in everyday life is water.

Give a reason why water is considered a 'universal solvent' but an alkali is not.

Water is a polar covalent compound. When it comes in contact with any substance it breaks the electrostatic forces holding the molecules of that substance. Thus, the molecules break loose from the substance and hence dissolve in water. Thus, water is called a universal solvent and an alkali is not.

Define the term 'solution' with reference to addition of sodium chloride to water.

A homogeneous mixture of a solute in a solvent is called a solution. E.g. When sodium chloride (solute) is dissolved in a solvent (water), it forms a solution of sodium chloride.

Define the term solvent with reference to addition of sodium chloride to water.

Solvent - The liquid or medium of dissolution which allows the solute to dissolve in it, so as to form a solution is called a solvent, e.g. water.

Why is iron sulphide a compound?

(a) Pure and impure substances

$$Pure\ Substances$$	$$Impure\ Substances$$
Pure substances have definite composition and definite physical and chemical properties.	Impure substances are made up of two or more pure substances mixed together in any proportion.
They are all homogeneous, i.e. their composition is uniform throughout the bulk.	They may be homogeneous or heterogeneous i.e. their composition is not uniform throughout the bulk.
Examples: elements and compounds	Examples: air, sea water, petroleum. a solution of sugar in water

(b) Homogeneous and heterogeneous substances

$$Homogeneous\ Substance$$	$$Heterogeneous\ Substance $$
It is a mixture where the components that make up the mixture are uniformly distributed throughout the mixture.	It is a mixture where the components of the mixture are not uniform or have localized regions with different properties.
Example - air, sugar water, rain water	Example - cereal in milk, vegetable soup

Define the term solute regarding the addition of sodium chloride to water.

Solute - The substance which dissolves or disappears in the solvent i.e. liquid to form a solution is called a solute. e.g. sodium chloride

When you add sodium chloride (salt) to the water, sodium chloride dissociates into sodium and chlorine ions.

How is distillation method different from evaporation?

1. During evaporation, the liquid vaporizes below its boiling point. But during the distillation process, the liquid vaporizes at its boiling point.

2. External heat energy is supplied during distillation whereas no external energy is required for the process of evaporation as it's a spontaneous process.

3. Evaporation process is slow but distillation is quick.

Classify the following substances into compounds and mixtures:
Carbon dioxide, air, water, milk, common salt, blood, fruit juice, and iron sulphide.

Compound and mixture are classified as,

Compounds:- Carbon dioxide, water, common salt, iron sulphide

Mixtures:- Air, milk, blood. fruit juice.

Give one example for each of the following types of mixtures:
(a) solid-solid homogeneous mixture
(b) heterogeneous mixture
(c) miscible liquids
(d) liquid-gas homogeneous mixture

(a) Solid-solid homogeneous mixture - Alloys of metals e.g. brass. bronze stainless steel etc.

(b) Solid-liquid heterogeneous mixture - Sand and water, mud and water, sugar and oil.

(d) liquid-gas homogeneous mixture - Air

Name the substance you will add to speed up sedimentation.

Alum.

Explain the term solute.

A solute is a substance which dissolves in other substances to form a solution. Solute is in smaller quantity in solution. It can also be defined as the substance which is dissolved in solvent.

Fill in the blank.
Chalk powder dissolved in water is an example of a ______ .

Chalk powder dissolved In the water is an example of a $$suspension$$.

On dissolving chalk powder in water, it is evident that it doesn't dissolve in it and we can see that the particles of the chalk powder with our naked eyes meaning that the particle size is greater than $$1000A ^o$$. Also, particles being heavier than water, settle down after some time.

Fill in the blank.
An ____ is a homogeneous mixture of two or more metals.

An alloy is a homogeneous mixture of two or more metals. The elements could be two mwtals or a metal and a nonmetal.

Fill in the blank.
Immiscible liquids are separated by using a _________ .

Answer: Separating funnel

Immiscible liquids are separated by using a separating funnel. For example, a mixture of water and oil can be separated by this method as they are immiscible liquids and separate out in layers depending on their densities.

Explain the term solvent.

Solvent: A solvent is a medium in which a solute dissolves. It is in large quantity in solution.

Solution = Solute + Solvent.

Define a pure substance.

A substance that has a constant composition and has consistent properties throughout the sample is known as a pure substance.

In chemistry, a pure substance consists of only one type of atom, molecule, or compound.

Examples of pure substances are tin, sulphur, water, etc.

Explain the term solution.

A solution is a homogeneous mixture of two or more components. The component present in a lower amount is known as solute and the component present in a higher amount is known as a solvent.

A solution can have more than one solute component. For example, a mixture of sugar, salt and water is homogeneous and is, therefore, a solution. The components, sugar and salt, present in lower amounts are solute and water is the solvent.

Give two examples of colloid.

A colloid is a kind of solution in which the size of the solute particles is intermediate between those in true solution and those in suspension. Examples of colloids are mayonnaise, milk, butter, gelatin, and jelly.

Give two examples of solvent other than water.

Acetone, ethanol, turpentine etc.

Differentiate between solution and suspension.

Solution:

1. It is an example of a homogeneous mixture.

2. Particle size is less than $$10^{-10}m$$.

3. Transparent.

4. Solute particles can not be filtered. The solution passes easily through filter paper.

Suspension-

1. It is an example of a heterogeneous mixture.

2. Particle size greater than $$10^{-7}m$$.

3. Opaque.

4. Particles of suspension do not pass through filter paper.

Explain why Fused $$CaCl_2$$ or conc.$$H_2SO_4$$ is used in a desiccator.

Fused $$CaCl_2$$ or conc.$$H_2SO_4$$ are deliquescent and they absorb moisture. Hence, they are used as the desiccator.

Differentiate between suspension and colloid.

Suspension-

1. Particle size greater than $$10^{-7}m$$.

2. Opaque.

3. Particles are visible to naked eyes.

4. Particles of suspension settle at the bottom of the container when the solution is kept undisturbed for some time.

5. Particles of suspension do not pass through filter paper.

Colloid-

1. Particles size between $$10^{-9}$$ to $$10^{-7}m$$.

2. Translucent.

3. Particles can be seen with the help of a powerful microscope.

4. Particles of colloids do not settle.

5. Colloidal particles pass easily through ordinary filter paper.

Answer the following question.

In one sample of brass, the following ingredients were found: copper $$(70\%)$$ and zinc $$(30\%)$$ Identify the solvent, solute, and solution from these.

Brass is an alloy made primarily of copper, usually with zinc. Brass as a solid solution consisting of zinc and other metals as solute dissolved in copper taken as solvent.

So, Solute: Zinc.

Solvent: Copper

Solution: Brass

Explain the difference between Separation by distillation and by Separating funnel.

Separation by distillation	Separation by separating funnel
1. This method is employed for separation of two miscible liquids.	1. This method is employed for separation of two immiscible liquids.
2. It is based on the difference points of two liquids.	2. It is based on the difference in the densities of the two liquids

Write the properties of metals.

Properties of metals are as follow:

1) Sonorous

2) Malleable

3) Ductile

4) High melting point

5) Good conductors of heat and electricity

What are ornaments made from? Why?

Ornaments are made from metals such as gold and silver are used for making jewellery because they are very lustrous.

Write the properties of metalloids.

Metalloids show the properties partially of metals and partially of nonmetals. examples are boron, silicon, germanium, etc.

Write the answer to the following question in your own words.
Which precaution will you take while using methods of distillation and separation by separating the funnel?

Precautions to be used during distillation:

The apparatus should be set properly with all the components fit well.
Never heat the system that is totally closed from the outside atmosphere to prevent the explosion.
Add boiling chips to reduce bumping (rapid boiling causing the liquid to expel out of the container).
Control the rate of heating so as not to overheat to avoid bumping.

Precautions to be used while using separating funnel for separation:

The funnel should be tightly fixed to the stand in an erect position.
The liquid in the funnel should be left undisturbed to allow it to separate.
The stopper should be removed carefully without disturbing the setup.

Explain why oil does not mix in water. However, oil and water become homogeneous if a sufficient quantity of detergent is added.

Oil and water are two immiscible liquids which means both of them to repel each other. But when we add a detergent to a solution containing water and oil, the mixture becomes homogeneous. This happens because of the detergent molecule. The detergent molecules have two ends. One of its ends holds on to a water molecule and the other end holds on to the oil molecule. These opposing forces help in dissolving the oil in water and thus making a homogeneous mixture.

Write the properties of the gold.

Properties of gold:

1) It is attractive, bright, and yellow in color

2) It is a lustrous metal

3) It is highly malleable

4) It is usually found in nature in a comparatively pure form.

Define a suspension.

A suspension is a heterogenous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye.

Which separation technique will you apply for the separation of sodium chloride from its solution in water?

Crystallization is a good method to separate sodium chloride from water. This method makes sure impurities are removed by filtration and only the pure salt crystallizes out when the mixture is heated and cooled.

Give any two examples of solvents other than water

Alcohol and petrol are examples of solvents other than water.

Write the answer to the following question in your own words.
Where are the methods of separation by distillation and by separating funnel used? Why?

Distillation and separating funnels are used in the separation of liquid mixtures. Distillation is a method that is used for separating two miscible liquids. It is based on the difference in the boiling points of two liquids. Distillation can either be simple or fractional. Simple distillation can be used for liquids that have a huge difference in their boiling points whereas fractional distillation is used in the case of liquids that have close boiling points. Distillation can be used in the production of gasoline, distilled water, xylene, alcohol, paraffin, kerosene apart from separating mixtures.

Separation using separating funnels is used in the case of immiscible liquids. It is based on the difference in the density of the two liquids. It can be used in the separation of oil from water etc, two different types of immiscible oils, etc.

Fill in the blank:
.............. water is used in making medicines.

Sterile/distilled water is used in making medicines since it is free from bacteria,viruses and any other impurity.

How dissolved impurities can be removed from water ?

Dissolved impurities from water can be removed by $$distillation$$.

Distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation. Distillation may result in essentially complete separation, or it may be a partial separation that increases the concentration of selected components in the mixture.

Explain homogeneous mixture with examples.

A homogeneous mixture is a solid, liquid, or gaseous mixture that has the same proportions of its components throughout any given sample
Example: air, salt solution, squash, etc.

A mixture of kerosene oil and water is what type of mixture?

A mixture of kerosene oil and water is a heterogeneous mixture. This is because the oil and water do not mix uniformly throughout the mixture.

How will you separate the mixture of water and mustard oil?

The mustard oil and water are immiscible liquids therefore they can be separated by using a separating funnel. The mixture of oil and water forms two separate layers because they are completely insoluble in each other.

Oil forms the upper layer while water forms the lower layers because the density of water is more than mustard oil. In separating funnel they are kept for resting, when two layers become stable by using separating funnel they are filtered one by one.

Which type of mixture is separated by separating funnel ?

Immiscible liquids in the mixture from different layers depending on their densities when allowed to stand undisturbed for some time, each layer can be separately taken out by using a separating funnel.

We can see from the figure, how kerosene oil and water can be separated by using a separating funnel.

1718465_1821360_ans_bcd062feb0c14497814199613cbd234e.png

Define compound with an example.

A compound is a pure substance, composed of two or more elements, chemically combined with one another in a fixed proportion.

For example: Water ($$ H_2O $$) and Methane ($$ CH_4 $$) etc.

What do you observe?

Two different layers of water and oil are seen in the beaker.

Oil and water are immiscible liquids. They do not mix with each other and form different layers based on their densities. Oil being less dense, makes the top layer.

How do you separate a mixture by using simple distillation? Explain with a diagram.

When the two liquids in the mixture are such that they boil without decomposition or chemical reaction and their boiling points have sufficient difference, more than $$ 25^0 C $$ then they can be separated by simple distillation.

Let us try to separate acetone(B.pt $$56^oC$$ ) and water(B.pt $$100^oC$$) from their mixture.

Take the mixture in a distillation flask.
Fit it with a thermometer.
Arrange the apparatus as shown in the figure.
Heat the mixture slowly keeping a close watch on the thermometer.
As soon it hits $$56^oC$$ acetone will start to boil and vaporise.
The acetone vapours condense in the condenser and can be collected from the condenser outlet.
Water is left behind in the distillation flask.

1721913_1821366_ans_e95deb382ed84f32aea8bcd37be1cf75.png

Define element.

An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Example : Carbon, oxygen, hydrogen, gold, silver and iron are examples of elements.

What is meant by pure substance ?

A pure substance consists of a single type of particle and all the constituents particles of that substance are the same in their chemical nature.

Name the apparatus used for separating a mixture of immiscible liquid .

A mixture of immiscible liquids is separated by using an apparatus called $$separating\ funnel$$.

Where is the fractionating column fitted in a distillation apparatus ?

The fractionating column is fitted in a distillation apparatus between the distillation flask and the water condenser.
1719237_1821522_ans_cea1902752cd45ad81c32b0e44b9a554.png

1719237_1821522_ans_cea1902752cd45ad81c32b0e44b9a554.png

Give scientific reason for the following:

Ornamental gold is an example of homogeneous mixture.

Ornamental gold is an alloy of gold and copper. Since the composition is uniform in alloys, they are considered to be homogeneous mixtures.

Give an example for each of the following
1.Suspension
2.Colloidal solution

1. Suspension - Sawdust added to water.
2. Colloidal solution - Milk.

What is meant by fractional distillation? How is it different from simple distillation? What part of the fractional distillation apparatus makes it more efficient and possesses an advantage over the simple distillation process? Explain using a diagram.
Give one example of the use of fractional distillation in an industry.

Distillation is a process of separation of two miscible liquids having different boiling points. In this process, a volatile liquid is first vaporised at its boiling point and its vapours are condensed to get back the liquid in pure form.

If the difference in boiling points of the two miscible liquids in the mixture is less than $$ 25^0 C $$, the method of fractional distillation is used to separate them.

The fractional distillation method is the same as simple distillation except that in the apparatus a fractionating column is fitted in between the distillation flask and the condenser.

It makes the apparatus more efficient. A fractionating column is a wide tube packed with glass beads, which provides a larger surface area for cooling. Vapours of liquid having a higher boiling point are condensed on the surface of the beads present in the lower part of the fractionating column, while the vapours of lower boiling point liquid move towards the top of the fractionating column. The length of the column also increases the efficiency of the process.

Example: In an oil refinery, the different petroleum products are separated by fractional distillation of crude petroleum.

1718969_1821540_ans_bc37bd4b7dd5481ebbac32c63b546048.png

Name a technique that can be used to separate salt from seawater.

To separate salt from seawater evaporation method can be used. Where seawater can be allowed to evaporate leaving the salt behind.

Give scientific reason for the following.
Mixture of sand and iron filings is heterogeneous mixture.

In sand and iron filings mixture, the components do not mix uniformly and are visible to the naked eye. The components can be separated easily using a magnet, which attracts the iron filings. So, it is a heterogenous mixture.

Give reason for the following:
Water is called a universal solvent.

Water dissolves many substances forming an aqueous solution. It can dissolve solids, liquids and gases. When a solid dissolves in water, the solid is the solute, the water is the solvent and the resultant liquid is the solution. So, it is said that water is a universal solvent.

Give definition of homogeneous mixture.

A mixture in which the compounds are uniform in the whole solution, its formation in the whole solution is the same and appears like a single substance is called a homogeneous mixture.

Example: Air is a homogeneous mixture of gases.

Define the term solution.

A solution is a homogenous mixture of two or more substances. The constituent substance which is in larger amount is called a solvent and that in smaller quantity is called a solute.

Does it advise to use ethylene glycol in radiators of cars in summer?

No, it is not advised to use ethylene glycol in radiators of cars in summer because ethylene glycol decreases the freezing point of water. It prevents the freezing of water of radiator in winter, so it is advised to use ethylene glycol in winter.

What is called suspension solution? Give example.

A heterogeneous solution in which the solute disperses in the solvent is called a suspension solution. The particle of the solute in the suspension solution remains floating in the solvent.

An example of this is gelatin, which stays suspended in water to form a gel.

Give a scientific reason for the following.
When a beam of light is passed through a suspension, its path is visible.

The particles of the suspension scatter a beam of light that is passing through it and make its path visible. It is due to the Tyndall effect.

What is called true solution? Give example.

A homogeneous solution that is stable and formed as a result of the complete dissolution of the solute in the solvent is called a true solution.

Examples: Air, vinegar, sugar solution, etc.

Give definition of heterogeneous mixture.

A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. It consists of two or more phases.

Heterogeneous mixtures can be separated by physical methods.

Example: Mixture of sand and sugar.

Why is water called a universal solvent?

Water is called the universal solvent because it is capable of dissolving more substances than any other liquid.

How will you separate oil and water from their mixture?

Oil, being lighter than water, will float on it. Two distinct layers are formed and slowly oil is allowed to flow into another container and is separated from the water. A separating funnel can also be used to separate the two.

What is called colloidal solution? Give example.

A heterogeneous solution in which the solute disperses evenly throughout the solvent and remain in the solvent giving it the appearance of a homogeneous solution is a colloidal solution.

An example of a colloidal solution is milk.

Find the odd one out:
Seawater, Muddy water, Table salt, Air.

Seawater is a mixture of many different substances.

Muddy water is a mixture of dirt and water.

Ordinary table salt is called sodium chloride. It is considered a substance because it has a uniform and definite composition.

Air is a mixture but not a compound. Its constituents can be separated.

Hence, table salt is not a mixture so it is an odd one among these.

Find out the relation and fill in the blanks.
Distillation :: Miscible liquids; Separting funnel :: ........................

Distillation is used for separating miscible liquids with the difference in their boiling points.

A separating funnel is used for separating immiscible liquids with the difference in their densities.

Hence answer is Immiscible liquids.

Explain homogeneous and hetergeneous mixture and give two examples of each.

Homogeneous mixture:
A mixture in which the components are uniform in the whole solution, its composition is the same throughout and it appears like a single substance, is a homogeneous mixture.

Examples:

Air is a homogeneous mixture of gases.
Salt solution is a homogeneous mixture of common salt and water.

Heterogeneous mixture:

A mixture in which each component of the mixture is identifiable and different and the properties of each component are different is called a heterogeneous mixture.

Example:

Mixture of salt and iron powder is a heterogeneous mixture.
Mixture of salt and sulphur powder is a heterogeneous mixture.

Haven't you noticed the caption "Shake well before use" in certain medicine bottles?
a. To which class do the substances in them belong to?
(Colloid, Solution, Suspension)
b. What is the relevance of such instructions on these bottles?

a. "Shake well before use" are written on medicine bottles belonging to class of $$Suspension$$.
b. It is used after shaking well because it is settled down after a long time.

From Gopu’s hand, the bottle containing coconut oil falls into a bucket containing water. Is it possible to separate oil and water?

Using a separating funnel, they can be separated. The denser water will be at the bottom and the lighter oil will be at the top. Water is removed through the tap.

Find the method of separation of components in following mixture:
Mixture of petrol and kerosene.

A mixture of petrol and kerosene can be separated by simple distillation because both the liquids are miscible and, the difference in their boiling point is more than $$25^oC$$. As petrol has a lower boiling point, so it evaporates first and is condensed and collected.

Find the method of separation of components in the following mixture:
(I) Water and acetone.

In the mixture of acetone and water, the acetone is a highly miscible liquid and dissolves readily in water. But the boiling point of water is $$100^\circ C$$ and boiling point of acetone is $$56^\circ C$$, that is a difference of $$44^ \circ C$$. So, the separation method is chosen in which the difference in their boiling point is considered having a difference more than $$25K$$. That is, the distillation process.

Classify and tabulate the mixtures gibe below into solution, colloid and suspension:
Milk, fog, atmospheric air, dilute acid, lime water, ink, smoke

Solution:- Dilute acid, atmospheric air
Colloid:- Milk, smoke, Fog, Ink
Suspension:- Lime water

Tabulate the differences between solution and suspension.

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Tabulate the two differences of solution and colloid.

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Find the method of separation of components in the following mixture:
drugs from the blood.

This process of separation of components of a mixture is known as chromatography. Kroma in Greek means color. This technique was first used for the separation of colors, so this name was given. Chromatography is the technique used for the separation of those solutes that dissolve in the same solvent.

Find the method of separation of components in following mixture:
Water and kerosene.

Water and kerosene are immiscible liquid and so they form two distinct layers. The two distinct layers of water and kerosene can be separated using separating funnel. Kerosene will form the top layer and water will form the lower layer in the separating funnel as water is denser than kerosene.

a. Which device is given in the above picture?
b. Why should this device doesnt use for separating petrol and kerosene mixture?
c. Which method is used to separate the mixture containing petrol and kerosene?

a. Separating funnel.
b. Petrol and kerosene are miscible liquids.
c. Fractional distillation.

Distinguish pure substances and mixtures.

Pure Substances and Mixtures:
Depending on their nature, substances can be classified into two:
1. Pure Substances,
2. Mixtures Materials
The substances made of particles of identical nature are called pure substances.
Eg: Water, common salt, sugar.
The substances made of particles of different nature are called mixtures.
Eg: Salt solution, sugar solution.

Write down some practical applications of fractional distillation.

Fractional distillation is used for :
1. Separating components to petroleum.
2. Separating components of air.

Fill in blank suitably:
Element - Atom,
Compound - _____.

Element - Atom,
Compound - Molecule.

When we use fractional distillation for separating components of mixture?

Fractional distillation is used to separate different liquids from a mixture of liquids. It is useful for separating ethanol from a mixture of ethanol and water. It is used when slight differences in their boiling points.

Using the given method write one example for separating components of the mixture:
(I) Distillation.

Distillation uses boiling to separate mixtures of liquid solutions.

For example, if you heat saltwater, the water in the solution will boil before the salt. The water will then evaporate leaving the salt behind.

Give one example where fractional distillation is used in real life.

Fractional distillation is used in the separation of the components of crude oil-kerosene, petrol, diesel etc.

Select the compounds from the following:
$$HCl, CO_2, O_2, NaCl, H_2, H_2O, Na $$

A compound is a substance formed when atoms of different elements combine chemically in a definite ratio.

Compounds are $$NaCl, CO_2, H_2O, HCl $$

List the points of differences between homogeneous and heterogeneous mixtures.

Homogeneous mixtures Heterogeneous mixtures
1. They have uniform compositions. 1. They have non-uniform compositions.

2. The components of homogeneous 2. They contain physically distinct parts.

mixtures are not physically distinct.

3. They have no visible boundaries of 3. They have visible boundaries of separation between the constituents.

the separation between the constituents.

Name three major products obtained by fractional distillation of petroleum and state one major use of each.

The major products obtained from the fractional distillation of petroleum are liquefied petroleum gas (LPG), refinery gas, and gasoline.

(i) LPG (Liquid Petroleum Gas) - It is a flammable gas commonly used in residential heating, cooking, and hot water systems. It also finds major applications as a fuel in cars, and also in industrial, agricultural, and manufacturing contexts.

(ii) Refinery gas - Refineries primarily process crude oil into motor and heating fuels, although other products can be made from them, such as gaseous fuels and feed gases for petrochemical processes, raw material for lubricant production, and asphalt.

(iii) Gasoline - Gasoline is a flammable liquid used as a fuel in cars, sport utility vehicles, light trucks, and motorcycles.

How will you purify sugar which has impurities of sodium chloride ?

Common salt and sugar both are soluble in water. So water cannot be used in the separation process. If we use alcohol, common salt will not be soluble, but sugar will be soluble. So salt can be separated by filtration and, sugar can be obtained by evaporating the alcohol.

An organic liquid decomposes below its boiling point. How will you purify it?

An organic liquid which decomposes below its boiling point can be distillation under reduced pressure i.e. vaccum distillation.

Two volatile liquid compounds A and B differ in their boiling points by $$15\, K.$$ Suggest a suitable method for their separation.

Two volatile compounds A and B which differ in their boiling points by $$15\, K$$ can be separated by fractional distillation.

How will you separate iodine from sodium chloride?

Either by sublimation or by extraction with $$CCl_{4}$$ followed by evaporation we can separate iodine from sodium chloride.

Suggest a suitable technique of separating naphthalene from kerosene oil present in a mixture.

Simple distillation is a suitable technique for separating naphthalene from kerosene oil present in a mixture. Simple distillation A method of separating mixtures based on differences in their volatilities in a boiling liquid mixture.

A mixture contains $$71$$% calcium sulphate and $$29$$% camphor. Name a suitable technique of separation for the components of this mixture.

Sublimation is a suitable technique of separation for the components of this mixture since camphor sublimes on heating.

What type of compounds are purified by sublimation?

Sublimation is a property of a substance to convert to a gaseous state from a solid-state without changing to a liquid state. This process is useful for purification of compounds that tend to sublimate, like naphthalene, camphor, etc.

Suggest methods for the separation of the following mixtures.

A mixture of liquid $$C\ (b.p- 353\,K)$$ and liquid $$D\ (b.p-413\,K).$$

A mixture of liquid $$C$$ and liquid $$D$$ is separated by simple distillation since the boiling points of the two liquids are widely apart.

How will you separate two components when their boiling points differ by a few degrees?

Fractional distillation is used to separate two liquids from their mixture when their boiling points differ by $$25^0C$$ or less.

Fractional distillation is the separation of a mixture into its parts or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. The vapours are later condensed and separated from the mixture.

When is the process of fractional distillation employed?

Fractional distillation is used to separate a mixture of two or more miscible liquids which boil without decomposition and for which the difference in boiling points is less than $$30^\circ C$$

Ex- Fractional distillation of crude oil-

Gasoline and many other chemicals are produced from crude oil using fractional distillation. Crude oil is heated until it evaporates.

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Fill in the blanks:
Liquids whose boiling points differ by about 10 K can be separated by ...............

Liquids whose boiling points differ by about 10 K can be separated by $$\underline{\text{fractional distillation}}.$$ This method is useful for liquids whose boiling points differ by less than 25 K.

How would you separate benzene (b.p. $$80^{\circ}C$$) from toluene (methyl-benzene (b.p. $$111^{\circ}C$$) with which it is miscible)?

Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which one or more fractions of the compound will vaporize. This is used to separate these two compounds.

Name a suitable technique of separation of the components from a mixture of calcium sulphate and camphor.

Sublimation can be used for the separation of the components from a mixture of calcium sulphate and camphor.
When the mixture is heated, camphor sublimes and calcium sulphate remains.
Sublimation is a process in which a solid is converted into vapour without passing into the liquid state.

Write four applications of colloids.

Colloids play a very significant role in nature and in our daily life. Some of the important applications of colloids are discussed below:

1) Medicines: Medicines in colloidal form are easily adsorbed by the body tissues and hence are more effective. Example: Milk of magnesia

2) Food: Many foods we eat are actually colloids. For example: jelly and cheese are colloids.

3) Cleaning: Items like sponge and foam that are used for cleaning are colloids.

4) Grooming: Substances like face creams, shaving creams that are used for personal grooming are colloids.

Distinguish between the true solution and colloidal solution.

1) A true solution is homogeneous in nature whereas a colloidal solution is heterogeneous.

2) The particle size of the solvent of the true solution is less than $$1\ nm$$ whereas in a colloidal solution it ranges between $$1 \ nm$$ to $$1000 \ nm$$.

3) The particles of the true solution are not visible even under ultramicroscope whereas, in the case of colloidal solution, they are visible to the naked eyes.

4) A true solution does not show the Tyndall effect whereas a colloidal solution shows the Tyndall effect.

Few mixture and their methods of sparation are given below the columns I and II respectively. Match the columns and mark the appropriate choice.

(A) Ether + toluene $$\rightarrow$$ Due to large difference in their boiling points, distillation method is used to separate them $$\rightarrow$$ 2.

(B) o-Nitrophenol + p-Nitrophenol $$\rightarrow$$ Since o-nitrophenol is steam volatile, and para isomer is non-volatile, mixture of p-nitrophenol and o-nitrophenol can be separated by steam distillation $$\rightarrow$$ 1.

(C) Benzoic acid + Benzaldehyde $$\rightarrow$$ Since benzoic acid is sublimable volatile compound, it can be separated by sublimation $$\rightarrow$$ 3.

(D) Fraction of crude oil $$\rightarrow$$ Since they have different boiling points, the substances in crude oil can be separated using fractional distillation. The crude oil is evaporated and its vapours allowed to condense at different temperatures in the fractionating column $$\rightarrow$$ 4.

Calculate the pH of the following solutions:
(i) 2.21 g of T $$lOH$$ dissolved in water to give 2 litre of solution. (Assume T$$l$$OH to be a strong base)
(ii) 0.49% w/v $$H_2SO_4$$ solution

i) $$2.2$$g of $$TlOH=\dfrac { 2.2 }{ 221.39 } mol=9.9\times { 10 }^{ -3 }$$

$$\therefore$$ concentration of $$TlOH=$$$$\dfrac { no.\quad of\quad moles }{ volume\quad of\quad solution } .N$$

$$=\dfrac { 9.9\times { 10 }^{ -3 } }{ 2 } N=4.95\times { 10 }^{ -3 }$$

$$\therefore$$ concentration of $${ OH }^{ - }=4.95\times { 10 }^{ -3 }N$$ ($$TlOH$$ strong base)

$$\therefore$$ $$pOH=-log\left[ { OH }^{ \left( - \right) } \right] =2.3$$ $$\therefore$$ $$prH=14-pOH=11.7$$

(ii) $$0.49$$% w/v $${ H }_{ 2 }{ SO }_{ 4 }$$ i.e. $$0.49$$gm of $${ H }_{ 2 }{ SO }_{ 4 }$$ is dissolved in $$100$$ml $${ H }_{ 2 }{ SO }_{ 4 }$$.

$$\therefore$$ concentration of $${ H }_{ 2 }{ SO }_{ 4 }$$$$=\dfrac { 0.49\times 1000 }{ 98\times 100 } =0.05\left( M \right) $$

$${ H }_{ 2 }{ SO }_{ 4 }\rightleftharpoons { 2H }^{ + }+{ SO }_{ 4 }^{ 2- }$$

$$\therefore$$ concentration of $${ H }^{ + },\left[ { H }^{ + } \right] =0.05\times 2N$$

$$=0.1N$$

$$\therefore$$ $$pH=-log\left[ { H }^{ + } \right] =-log\left( 0.1 \right) =1$$

Write any three differences between "True solution" and "Suspension"?

True solution	Suspension
It is homogeneous mixture in nature	It is heterogeneous mixture in nature
it is very stable	It is unstable
It does not scatter beam of light and hence it do not show tyndall effect	It scatters the beam of light and hence it shows tyndall effect

Out of a colloid, solution, and a suspension?
(a) Which one has the smallest particles?
(b) Which one has the largest particles?

(a) The solution has the smallest particles, the diameter of these particles is less than 1nm.

(b) The suspension has the largest particles, the diameter of these particles are more than 100nm.

The size of the colloidal particles ranges from 1 nm to 1 micrometre.

Differentiate between :
(a) Solution and suspension
(b) Suspension and colloid

$$Solution:$$
A solution mix thoroughly together because particles of a solid are very tiny.
Solute particles are dispersed in the solvent as single molecules or ions.
The diameter of the dispersed particles ranges from $$1Å$$ to $$10 Å. $$
Example: Saltwater, bleach

$$Suspension :$$
Suspension doesn’t mix together entirely, or if they do, the particles may become unmixed and fall to the bottom.
Dispersed particles or solutes in suspension are larger than solutes of solution.
Diameter of these particles is of the order $$2000Å$$ or more.
Example- sand stirred into water, soot in the air

$$Colloids:$$
Colloids solutions are colloids suspension are intermediate between true solutions and suspensions.
Diameter of the dispersed particles in the solvent of colloid solution ranges from $$10Å$$ to $$2000Å$$.
Example- milk, butter

A solution have mass $$250gm$$ and concentration $$10$$%. Find amount of the mass of solute present in a solution.

Mass % of solution = $$(mass\ of\ solute \times 100)/ mass\ of\ solution$$

$$10 = mass\ of\ solute \times 100 / 250$$

$$mass\ of\ solute = 10 \times 250 / 100$$

$$mass\ of\ solute = 25gm$$

Amount of mass of solute present in solution is $$25gm$$.

Draw a diagram of the type fractionating column. When do we require such type of a column for separating two liquids? Explain the principle involved in the separation of components of a mixture of liquids by using a fractionating column. What industrial applications does this process have?

If the difference in boiling points of two liquids is not much, simple distillation cannot be used to separate them. The vapours of such liquids are formed within the same temperature range and are condensed simultaneously. The technique of fractional distillation is used in such cases. In this technique, vapours of a liquid mixture are passed through a fractionating column before condensation. The fractionating column is fitted over the mouth of the round bottom flask. Vapours of the liquid with higher boiling point condense before the vapours of the liquid with lower boiling point. The vapours rising up in the fractionating column become richer in more volatile component. By the time the vapours reach to the top of the fractionating column, these are rich in more volatile component.
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Two liquids (A) and (B) can be separated by the method of fractional distillation.
The boiling point of liquid (A) is less than boiling point of liquid (B). Which of the liquids do you expect to come out first in the distillate? Explain.

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Differentiate between true solution, colloidal solution and suspension.

$$True\ solution$$

$$Suspension$$

$$Colloidal\ solution$$

Homogenous mixture

Heterogeneous mixture

Appearance: Transparent

Appearance:
Opaque

Appearance:
Translucent

Particle size:
very small, cannot be seen by naked eye

Particle size: large, can be seen by naked eye

Particle size:
between true solution and suspension, cannot be seen by naked eye

Solute particles do not settle down when left undisturbed

Solute particles settle down when left undisturbed

Solute particles do not settle down when left undisturbed

Filtration separation -not possible

Filtration separation - possible

Filtration separation - not possible

E.g. salt solution

E.g. sand in water

E.g. milk

You have a mixture of three liquids $$A, B$$ and $$C$$. There is a large difference in the boiling points of $$A$$ and the rest of the two liquids i.e., $$B$$ and $$C$$. The boiling point of liquids $$B$$ and $$C$$ are quite close. Liquid $$A$$ boils at a higher temperature than $$B$$ and $$C$$ and the boiling point of $$B$$ is lower than $$C$$. How will you separate the components of the mixture? Draw a diagram showing setup of the apparatus for the process.

Liquids having different boiling points vaporize at different temperatures. The vapors are cooled and then liquids so formed are collected separately. Liquid $$A$$ can be separated from $$B$$ and $$C$$ because of the large difference in boiling point. Liquid $$B$$ and $$C$$ have boiling points very close to each other and cannot be separated by simple distillation hence separated by fractional distillation. Liquid $$B$$ distilled first because the order of boiling points of $$A, B$$ and $$C$$ are as follows: $$B < C < A$$,
1664648_1794866_ans_00484f3e2d7f41daa11529ff8a4d0d8d.png

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Alcohol (boiling point $$97^0C$$) was mixed with a hydrocarbon (boiling point $$68^0C$$) by mistake. Suggest a suitable method to separate the two compounds. Explain the reason for your choice.

A mixture of alcohol and hydrocarbon can be separated by simple distillation because both components have a large difference in their boiling points(more than $$25^oC$$). When the temperature is raised to the boiling point of the low boiling liquid i.e., hydrocarbon, the vapours will consist only of the hydrocarbon without any contamination of alcohol as their boiling points are far apart. These vapours can be condensed back to get the hydrocarbon.

Constituent substances of a colloid cannot be separated by ordinary filtration. Give reason.

Constituent substances of a colloid cannot be separated by ordinary filtration because the size of the particles in a colloid (or colloidal solution) is bigger than those in a true solution but smaller than those in suspension. It is between 1 nm to 100 nm in diameter. The size of ordinary filter paper is more than 100 nm due to which colloidal particles are passed through the pores of a filter paper. Due to which, we prefer to use ultrafilter paper so that, filtration of colloidal particles takes place easily.

Suggest the method to purify:
Camphor containing salt impurity

The mixture should be taken in a china dish. On heating, camphor, sublimates, it directly converts to vapour. and the common salt is left as a residue in the dish. Thus camphor and common salt can be separated by sublimation.

Name the technique to separate camphor from salt.

To separate camphor from salt, sublimation method can be used.

So, the technique used for separation of camphor from salt is sublimation.

Suggest the method to purify:
Kerosene oil containing water

Kerosene and water are immiscible liquids. They can be separated using a Separating funnel. Kerosene forms the upper layer as it is lighter than water.

Because of which they can be collected independently.

Which separation techniques will you apply for the separation of ammonium chloride from a mixture containing sodium chloride and ammonium chloride?

The technique used for separation of ammonium chloride from a mixture containing sodium chloride and ammonium chloride is sublimation because ammonium chloride is a sublimable substance and water is a non-sublimable substance.

Suggest the method to separate:
Sugar and Naphthalene

A mixture of sugar and naphthalene can be separated by dissolving in water. Sugar dissolves in water and, so it will form a solution with water. Later the sugar can be separated from water by crystallization. Naphthalene does not dissolve in water so, it can be separated by filtering the sugar solution.

Naphthalene can also be separated by sublimation from sugar at room temperature. The vapor of naphthalene can be collected and solidified. But, if the temperature is lower than room temperature heating is required for naphthalene to sublime. But heating may cause the sugar to get charred. So we have to carefully select the method based on the conditions.

Is Matter Around Us Pure - Class 9 Chemistry - Extra Questions

$$H_2O$$ contains hydrogen and oxygen but it is a pure substance. How?

What are the components of solution?

Define a compound.

Name the liquid which evaporates and then condenses during the process of distillation.

Cloud is a colloidal suspension of water droplets in air.If true then enter 1, else enter 0.

State two ways in which you can separate a mixture of sand and sugar.

Smoke is an aerosol and a colloidal solution of carbon in air.If true then enter 1, else enter 0.

Two or more elements combine to form ...............

Table salt is made from sodium and chlorine which can be poisonous. Still we can eat table salt without getting poisoned. Why?

How will you obtain $$NH_4Cl$$ from a mixture of $$NH_4Cl$$ and $$KCl$$?

"The properties of the product are different from those of the constituents". State whether this statement best describes an element, a compound or a mixture.

What are pure substances? Give two example of pure substances.

How will you separate a mixture of common salt, chalk powder and powdered camphor? Explain.

What are immiscible liquids?

A few mixtures are given above. Tabulate the methods to separate their components and give the reasons for selecting the method.

How will you purify a liquid having non-volatile impurities?

Suggest methods for the separation of the following mixtures.A mixture of liquid $$A\ (b.p-365\,K)$$ and liquid $$B\ (b.p-356\,K).$$

Classify the following substances into elements, compounds and mixtures:(i) Milk (ii) 22-carat gold (iii) iodized table salt (iv) Diamond (v) Smoke (vi) Steel (vii) Brass (viii) Dry ice (ix) Mercury (x) Air (xi) Aerated drinks (xii) Glucose (xiii) Pertol/Diesel/Kerosene oil (xiv) Steam (xv) Cloud

Suggest a method to purify camphor containing traces of common salt.

A solution is prepared by dissolving certain amount of solute in 500 g of water. The percentage by mass of solute in solution is 2.38. Calculate mass of solute.

A solution that has relatively less amount of solute with respect to the solvent is called a ________ solution.

Ammonium chloride can be separated from common salt by the method of ................

If true enter $$1$$, else enter $$0$$.A standard solution is one whose concentration is not known.

Why is air considered as a mixture?

What do you mean by:(a) Molecule of an element(b) Molecule of a compound, with examples

Can their be possibility of solid solutions?

The major component of steel is ________.

Define heterogeneous mixtures and write its types.

What is distillation?

Blood is an example of ________.

Water is good solvent for ionic compounds.

Give example of following type of Colloid. Emulsion

Give example of following type of Colloid. Solid sol

Give example of following type of Colloid. Gel

The process of settling of sand, when a mixture of sand and water is left undisturbed for some time is known as ______________.

Suggest a suitable method to separate the components of the mixture of two volatile components with an appreciable difference in boiling points.

Under which category of mixtures will you classify alloys and why?

________ (Matter/Atom) can be classified chemically into pure substances and mixtures.

A mixture of iodine and sand are separated by method of _______ . (filtration/sublimation)

A mixture of oil and water can be separated by using ______ (separating/filtration) funnel.

How is 'chromatography' applied in the separation of coloured constituents present in a mixture of ink?

Define crystallization.

What would you observe when crystals of copper (II) sulphate and iron (II) sulphate are separately heated in two test tubes?

Explain the method of crystallization.

Blood is a _________.true solutioncolloidsuspension(Give your answer using respective number)

Water is purified for scientific purposes by distillation. Describe the process.

Why is water called an universal solvent?

Explain the following giving examples.$$(a)$$ Saturated solution$$(b)$$ Pure substance$$(c)$$ Colloid$$(d)$$ Suspension

Classify each of the following as a homogeneous or heterogeneous mixture: Soda water, wood, air, soil, vinegar, filtered tea.

Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.

Which of the following materials fall in the category of a pure substance?$$(a)$$ Ice$$(b)$$ Milk$$(c)$$ Iron$$(d)$$ Hydrochloric acid$$(e)$$ Calcium oxide$$(f)$$ Mercury$$(g)$$ Brick$$(h)$$ Wood$$(i)$$ Air

Identify the solutions among the following mixtures.$$(a)$$ Soil$$(b)$$ Seawater$$(c)$$ Air$$(d)$$ Coal$$(e)$$ Soda water

What is the difference between distillation and fractional distillation?

True or False.The properties of compounds are the same as those of the constituent elements.

State True or False.Distilled water cannot be separated into its constituents by physical methods.

Is air considered a solution? Explain.

Match the examples with suitable separation process:

Distinguish between true solution and colloidal solution.

State differences between aerosol and foam?

Can we separate the compounds of an azeotropic mixture by fractional distillation? Explain

In centrifuge how are particles of different densities separated?

Differentiate true solution and colloidal solution.

Colloidal solution of solid in liquid is called ________.

What type of colloid is formed when a gas is dispersed in a liquid? Give an example.

Answer in one word or one sentence.Ornamental gold-containing copper is an example of what type of solution?

How will you separate oil and water from their mixture?

How much copper sulphate will be required to saturate 100 g of a dilute aqueous solution of $$CuSO_4$$ at $$25^oC$$ if 10 g of the dilute solution leave on evaporation and drying 1.2 g of anhydrous $$CuSO_4$$ in water at $$25^oC$$ is 25.

Define the following terms:(i) Solution(ii) Solute

What is meant by a pure substance? Give examples.

State the properties of solution.

Define elements, compounds and molecules.

Give a reason for the following observations. (a) Naphthalene balls disappear with time without leaving any solid. (b) We can get the smell of perfume sitting several meters away.

Name the method you will use to separate two immiscible liquids.

What do you observe on the filter paper on which a drop of ink is placed, and as the water rises on it?

Give two examples of homogeneous mixture.

Differentiate between homogeneous and heterogeneous mixtures with examples.

In one sample of brass, the following components were found: Copper $$(70\%)$$ and zinc $$(30\%)$$. Identify the solvent, solute, and solution from these.

Answer in one word/ a few words.A pure substance formed when atoms or molecules of different elements combine.

What kind of mixture is gunpowder?

Cloud is a colloidal suspension of water droplets in air.

If true then enter 1, else enter 0.

Smoke is an aerosol and a colloidal solution of carbon in air.
If true then enter 1, else enter 0.

Suggest methods for the separation of the following mixtures.

A mixture of liquid $$A\ (b.p-365\,K)$$ and liquid $$B\ (b.p-356\,K).$$

Classify the following substances into elements, compounds and mixtures:
(i) Milk (ii) 22-carat gold (iii) iodized table salt (iv) Diamond (v) Smoke (vi) Steel (vii) Brass (viii) Dry ice (ix) Mercury (x) Air (xi) Aerated drinks (xii) Glucose (xiii) Pertol/Diesel/Kerosene oil (xiv) Steam (xv) Cloud

If true enter $$1$$, else enter $$0$$.
A standard solution is one whose concentration is not known.

What do you mean by:
(a) Molecule of an element
(b) Molecule of a compound, with examples

Give example of following type of Colloid.
Emulsion

Give example of following type of Colloid.
Solid sol

Give example of following type of Colloid.
Gel

Blood is a _________.
true solution
colloid
suspension
(Give your answer using respective number)

Explain the following giving examples.
$$(a)$$ Saturated solution
$$(b)$$ Pure substance
$$(c)$$ Colloid
$$(d)$$ Suspension

Classify each of the following as a homogeneous or heterogeneous mixture:
Soda water, wood, air, soil, vinegar, filtered tea.

Which of the following materials fall in the category of a pure substance?
$$(a)$$ Ice
$$(b)$$ Milk
$$(c)$$ Iron
$$(d)$$ Hydrochloric acid
$$(e)$$ Calcium oxide
$$(f)$$ Mercury
$$(g)$$ Brick
$$(h)$$ Wood
$$(i)$$ Air

Identify the solutions among the following mixtures.
$$(a)$$ Soil
$$(b)$$ Seawater
$$(c)$$ Air
$$(d)$$ Coal
$$(e)$$ Soda water

True or False.
The properties of compounds are the same as those of the constituent elements.

State True or False.
Distilled water cannot be separated into its constituents by physical methods.

Answer in one word or one sentence.

Ornamental gold-containing copper is an example of what type of solution?

Define the following terms:
(i) Solution
(ii) Solute

Give a reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several meters away.

Answer in one word/ a few words.

A pure substance formed when atoms or molecules of different elements combine.

Answer in one word/ a few words
The simplest form of a pure substance made up of only one kind of atom -_______________.

Answer in one word/ a few words.
A homogeneous mixture of solvent and solute.

Which of the following are 'Pure substances'?
Ice, Milk, Iron, Hydrochloric acid, Calcium oxide, Mercury, Brick, Wood, Air

Choose the solution form among the following mixtures:
Soil, Sea-water, Air, Coal, Soda-water

Which of the following are not compounds?

Chlorine gas, Potassium chloride, Iron powder, Iron Sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond

Give two characteristics each of:
(a) Pure substances
(b) Mixtures

Identify colloid from the following mixtures:
Muddy water, sugar in water, ink, blood, soda water, foam

Explain the following giving examples:
(a) Saturated solution
(b) Unsaturated solution
(c) Suspension.

Give one example of the following:
Aerosol

You are provided with soda water, milk, and muddy water. How can you differentiate between them in terms of:
(i) Homogeneity
(ii) Filtration
(iii)Tyndall effect

Give one example of the following:
Solution

A mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of and the lower layer will be that of .

Give two examples for each of the following :
(a) Metals
(b) Non-metals
(c) Metalloids
(d) Noble gases