breaking and dispersion into colloidal state

precipitation of solid from colloidal dispersion

May have molecular weight as low as 1 or higher than 200,000

Changes $$\displaystyle \Delta G$$ for an equation

Acts by increasing the rate of the forward reaction more than the reverse reaction

Raises the equilibrium constant of a system

Does not react chemically during the course of a reaction

MCQ Questions for Class 12 Engineering Chemistry Surface Chemistry Quiz 6

Physisorption is non-specific.

0%
True
0%
False

The substance on whose surface adsorption takes place is called an _______ .

0%
absorbent
0%
absorbate
0%
solute
0%
solvent

The catalyst in photosynthesis is:

0%
sunlight
0%
water
0%
chlorophyll
0%
$CO_2$

Explanation

The work of chlorophyll is to absorb light energy from sunlight and transfer it to other molecules used for a process of photosynthesis. This energy is utilized in synthesize carbohydrates using $CO_2$ .

Further, it also doesn't use in a reaction of photosynthesis hence it acts as the catalyst in this reaction.
Complete balanced chemical equation is $6H_2O + 6CO_2 \rightarrow C_6H_{12}O_6 + 6O_2$

Cleansing action of soaps includes:

0%
formation of micelles
0%
emulsification of oil or grease
0%
lowering of surface tension of water
0%
all of the above

Which metal is used as a catalyst in the hydrogenation of oils?

0%
Iron
0%
Sodium
0%
Nickel
0%
Gold

Explanation

Hydrogenation is a chemical reaction between molecular hydrogen $(H_2)$ and another compound or element, usually in the presence of a catalyst such as nickel, palladium, or platinum. The process is commonly employed to reduce or saturate organic compounds.

The colloidal dispersion of a liquid in a liquid is called:

0%
mixture
0%
emulsion
0%
precipite
0%
none of these

Whenever a mixture of gases is allowed to come in contact with a particular adsorbent under the same conditions, the more strong adsorbate is adsorbed to greater extent irrespective of its amount present. For example,

$H_2O$ is adsorbed to more extent on silica gel than

$N_2$ and

$O_2$ . This shows that some adsorbates are preferentially adsorbed. It is also observed that preferentially adsorbable adsorbents can displace a weakly adsorbed substance from the surface of an adsorbent.

Which of the gas can displace remaining all the gases?

0%
$O_2$
0%
$N_2$
0%
$CO$
0%
$H_2$

Explanation

Whenever a mixture of gases is allowed to come in contact with a particular adsorbent under the same conditions, the more strong adsorbate(Depends on factors like polarity and chemical reactivity) is adsorbed to greater extent irrespective of its amount present, e.g.

$H_2O$ is adsorbed to more extent on silica gel than

$N_2$ and

$O_2$
Here, among given gases, CO is most reactive and most polar so it will replace all other gases.

When

$KClO_3$ is heated, it decomposes into

$KCl$ and

$O_2$ . If some

$MnO_2$ is added, the reaction goes much faster because :

0%
$MnO_2$ decomposes to give $O_2$
0%
$MnO_2$ provides heat by reacting
0%
Better contact is provided by $MnO_2$
0%
$MnO_2$ acts as a catalyst.

Explanation

Thermal decomposition of

$KClO_3$ is found to be accelerated by the presence of

$MnO_2$ . Here,

$MnO_2$ (foreign substance) act as a catalyst

$2KClO_3+[MnO_2]\longrightarrow 2KCl + 3O_2\uparrow + [MnO_2]$

A catalyst is a substance, which increases the rate of reaction without itself being consumed at the end of the reaction, and the phenomenon is called catalysis. There are some catalysts which decrease the rate of reaction and such catalysts are called negative catalyst. Obviously, the catalyst accelerating the rate will be positive catalyst. However, the term positive is seldom used and catalyst itself implies positive catalyst. Catalysts are generally foreign substances but sometimes one of the product formed may act as a catalyst and such a catalyst is called "auto catalyst" and the phenomenon is called auto catalysis.

Activated charcoal is used to remove colouring matter from pure substances. It works by:

0%
oxidation
0%
reduction
0%
bleaching
0%
adsorption

In physical adsorption, the adsorbent and adsorbate are held together by the:

0%
Ionic force
0%
Covalent force
0%
Van der Waal's force
0%
H-bonding

Explanation

In physical adsorption, the force of attraction between the molecules of the adsorbate and adsorbent is of weak Van der Waal's force. This is a weak force of attraction.

So, the correct option is

$C$

The action of cleaning of oily dirt by soap is based on

0%
Solubility in water
0%
Hydrophilic property
0%
Hydrophobic property
0%
Presence of both hydrophilic and hydrophobic groups

Rate of physical adsorption increases with:

0%
decrease in surface area
0%
decrease in temperature
0%
decrease in pressure
0%
All of the above

Cow milk, an example of natural emulsion is stabilised by:

0%
Fat
0%
Water
0%
Casein
0%
Mg $^{2+}$ ions

The metal used as a catalyst in the hydrogenation of oil is:

0%
sodium
0%
nickel
0%
mercury
0%
manganese

A substance which alters the rate of reaction:

0%
reactant
0%
product
0%
ingredient
0%
catalyst

If the adsorbate is held on the surface of an adsorbent by force of van der Waals type, the adsorption is called:

0%

van der Waals adsorption
0%
physical adsorption
0%
physisorption
0%
All of these

The cleaning action of a soap is due to soap lather, which reduced the interfacial tension and solubilises the oily dirt into the water by emulsification.

0%
True
0%
False

Which metal is used as a catalyst in the hydrogenation of oils?

0%
Iron
0%
Sodium
0%
Nickel
0%
Gold

Adsorption increases with increase in temperature in Physisorption.

0%
True
0%
False

Which of the following is/are true for physisorption?

0%
Easily liquefied gases are more adsorbed.
0%
Weak van der Waals forces cause the adsorption process.
0%
Only unimolecular layer formation.
0%
Adsorbtion increases with rise in temperature.

Weak van der Waal forces are responsible for Physisorption.

0%
True
0%
False

Toothpaste and mud are examples of :

0%
foam and sol respectively
0%
sol
0%
gel and emulsion respectively
0%
foam

The physical adsorption of gases on the solid surface is due to:

0%
covalent bond
0%
hydrogen bond
0%
ionic bond
0%
van der wal's force

Match the columns.

I)	Dust	a)	Gel
II)	Milk	b)	Emulsion
III)	Toothpaste	c)	Solid aerosol
IV)	Opal	d)	Sol

0%
I-d, II-a, III-c, IV-b
0%
I-c, II-b, III-d, IV-a
0%
I-b, II-c, III-a, IV-d
0%
I-a, II-d, III-b, IV-c

The catalyst used in preparation of oxygen from hydrogen peroxide is:

0%
manganese dioxide
0%
magnesium oxide
0%
manganese oxide
0%
manganese sulphate

Explanation

Manganese dioxide lowers the activation energy which makes the reaction of decomposition of hydrogen peroxide to oxygen fast. It allows more molecules of $H_2O_2$ to undergo decomposition in a shorter period of time.

Balanced chemical equation of reaction is $2H_2O_2(aq) \xrightarrow{{MnO_2(s)}} 2H_2O(l)+O_2(g)$

Which of the following rules states that with the increase of every

${ 10 }^{ \circ }C$ temperature the rate of metabolic activity gets doubled?

0%
Van't Hoff's rule
0%
Bergman's rule
0%
Allen's rule
0%
Jordon's rule

Explanation

Van't Hoff's rule states that the velocity or the metabolic activity is doubled for every rise of 10

$^0$ C in temperature.

Bergmann's rule states that species of larger size are found in colder environments and species of smaller size are found in warmer environments.

Allen's rule states that body form is linear in warm climates and more rounded and compact in cold climates. Round body shapes give a smaller surface area to volume ratio.

Jordon's rule states that fin ray, vertebrae or scale numbers increase with the decrease in temperature.

Thus, the correct answer is option A.

Animal charcoal is used in decolorising colour of liquids because it is a good :

0%
adsorbate
0%
adsorbent
0%
oxidising agent
0%
reducing agent

Peptization denotes:

0%
hydrolysis of proteins
0%
digestion of food
0%
breaking and dispersion into colloidal state
0%
precipitation of solid from colloidal dispersion

Explanation

$Explanation:$

Peptization is a process in which colloidal solution is prepared by adding electrolyte to a precipitate. The electrolyte is added called as peptizing agent. This peptization process also called as deflocculation.

Example: when the ferric chloride solution is added to the ferric hydroxide precipitate, it gives sol of ferric hydroxide.

Therefore , we can say that in peptization, precipitate breaks and disperse into a colloidal solution.

$Final\ Answer:$ Option

$C$ .

The change in energy for the overall reaction is defined by letter :

0%
A
0%
B
0%
C
0%
Y
0%
X

Find the false statement for chemical catalysts ?

0%
They are not consumed during the chemical reaction
0%
They cannot make nonspontaneous reactions occur
0%
They do not have to be the same phase as the reactant molecules
0%
They shift equilibrated reactions to the product's side
0%
Enzymes are biological catalysts

Statement I: Above reaction is exothermic.
Because
Statement II: Energy difference B is greater than energy difference A.

0%
true, true, correct explanation
0%
true, true, not correct explanation
0%
true, false
0%
false, true
0%
false, false

When two immiscible liquids are shaken together vigorously, it may form :

0%
a solution
0%
a tincture
0%
a sediment
0%
a hydrated solution
0%
a colloidal dispersion

Recorded data:
Before

$:$

$CuO+$ porcelain boat

$=62.869$ g

$CaCl_2+$ U-tube

$=80.483$ g
After:Porcelain boat

$+$ contents

$=54.869$ g

$CaCl_2+$ U-tube

$=89.483$ g
Reactions:

$Zn(s)+2HCl(aq)\rightarrow ZnCl_2(aq)+H_2(g)$ then

$H_2(g)+CuO(s)\rightarrow H_2O(g)+Cu(s)$
What was the reason placing tube of

$CaCl_2$ between the generator and the tube containing the porcelain boat?

0%
To absorb evaporated HCl
0%
To absorb evaporated $H_2O$
0%
To slow down the gases released
0%
To absorb the evaporated Zn particles
0%
To remove the initial air that passes through the tube

Explanation

A tube of

$\displaystyle CaCl_2$ was placed between the generator and the tube containing the porcelain boat to absorb evaporated

$\displaystyle H_2O$ .

$\displaystyle CaCl_2$ is a drying agent. It removes moisture from hydrogen gas.

Peptisation is a process in which:

0%
precipitation becomes true solution
0%
true solution becomes a suspension
0%
a colloid gets coagulation
0%
a suspension gets converted into a colloid

An uncatalyzed reaction' s progress diagram is shown by solid line. Which of two dotted lines represents the same reaction in the presence of catalyst?

0%
A
0%
B
0%
C
0%
D
0%
E

Activation energy of the reaction is corresponded by letter :

0%
A
0%
B
0%
C
0%
Y
0%
X

After observing the graph, which statement tells that the chemical reaction is exothermic?

0%
The potential energy at point 2
0%
The energy difference between points 1 and 2
0%
The time elapsed between points 2 and 3
0%
The energy difference between points 1 and 3
0%
The time needed to reach point 3

A catalyzed reaction mechanism has a ____ activation energy and thus, causes a _____ reaction rate.

0%
higher, lower
0%
higher, higher
0%
lower, higher
0%
lower, steady
0%
higher, steady

Delta formation at the mouth of river takes place by:

0%
coagulation of negative salt ions and positive river particles
0%
coagulation of positive salt ions and negative river particles
0%
coagulation of positive salt ions and positive river particles
0%
coagulation of negative salt ions and negative river particles

A catalyst :

0%
Changes $\displaystyle \Delta G$ for an equation
0%
Acts by increasing the rate of the forward reaction more than the reverse reaction
0%
Raises the equilibrium constant of a system
0%
May have molecular weight as low as 1 or higher than 200,000
0%
Does not react chemically during the course of a reaction

Explanation

R.E.F image

Characteristics of catalyst are as follows:

1. The catalyst remains unchanged (in mass and chemical composition ) in the reaction (Activity of catalyst)

2. A small quantity of the catalyst is required. e.g. one mole of colloid pt catalyses

$10^{8}LH_{2}O_{2}$

3. The catalyst does not change the equilibrium constant. But the equilibrium approaches earlier.

4. Specificity of catalyst:

The catalyst is specific in nature. It means by the change of catalyst, nature of the product changes or

specific catalyst for a specific reaction.

5. The catalyst can not make impossible reaction to occur and does not initiate a reaction.

Which of the following pairs of colloidal solutions have dispersed phase as liquid and dispersed medium as gas?

0%
Fog, mist
0%
Butter, milk
0%
Fog, smoke
0%
Smoke, foam

What is a sol?

0%
A solid dispersed in a liquid
0%
A liquid dispersed in a gas
0%
A gas dispersed in a liquid
0%
A gas dispersed in a solid

Increased with the addition of a catalyst :

0%
Standard voltaic potential
0%
Entropy
0%
Enthalpy
0%
Reaction rate
0%
Gibbs free energy

Catalyst used in Rosenmund reaction is:

0%
$Sn$
0%
$Zn/HCl$
0%
$Pd/BaSO_4$
0%
$Ni$

Explanation

A catalyst used in Rosenmund reaction can be prepared by reduction of $palladium(II) \space chloride$ solution in the presence of $BaSO_4$

The Palladium Catalyst used in Rosenmund’s reduction must be poisoned with $BaSO_4$ because the untreated catalyst $Palladium (Pd)$ is too reactive and will undergo over reduction forming other products.

To which of the following category does ice-cream belong?

0%
Solution
0%
Emulsion
0%
Element
0%
Suspension

Which letter corresponds to the activation energy in this reaction without the addition of a catalyst?

0%
A
0%
B
0%
C
0%
D
0%
E

The process of separating of cream from milk is called :

0%
Emulsification
0%
Demulsification
0%
Emulsions
0%
Electro-osmosis

Which one of the following systems has the smallest sized domains in its dispersed phase?

0%
Nanoemulsion
0%
Coarse suspension
0%
Coarse emulsion
0%
Microemulsion

Milk is an example of :

0%
Suspension
0%
True solution
0%
Emulsion
0%
None of the above

An example of a colloid which is an emulsion is :

0%
Wipped cream
0%
Mayonnaise
0%
Fog
0%
Gelatin

CBSE Questions for Class 12 Engineering Chemistry Surface Chemistry Quiz 6 - MCQExams.com

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Practice Class 12 Engineering Chemistry Quiz Questions and Answers

CBSE Questions for Class 12 Engineering Chemistry Surface Chemistry Quiz 6 - MCQExams.com

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Practice Class 12 Engineering Chemistry Quiz Questions and Answers

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