Metals And Non Metals - Class 10 Chemistry - Extra Questions

Enumerate some of the physical properties of non-metals.

Properties of non-metals:
1) Are non-ductile, not flexible and hence cannot be drawn into wires.
2) Are non-sonorous, do not make a sound when struck.
3) Generally bad conductors of electricity.
4) Generally do not have a characteristic shine also known as lustre.


What is a sickle that is used to cut sugarcane made from? Why? 

A sickle to cut sugarcane is made out of iron since it is very hard and strong.


Generally, non-metals are not lustrous. Name a non-metal which is lustrous.

Iodine is a non metal whose crystals has lustrous property.


State the conditions under which the following metals react with water. Give equations for each reaction.
(i) Na
(ii) Mg
(iii) Fe

(i) 
The conditions under which the sodium metal (Na) will react with water is as follows:
$$\bullet$$  Sodium can react violently with normal cold water without any special conditions.
$$\bullet$$  When sodium reacts with cold water, it forms sodium hydroxide(NaOH), hydrogen gas$$(H_2)$$ and a lot of heat.
$$\bullet$$  The chemical reaction involved is as follows:
    $$2Na + 2H_2O\rightarrow 2NaOH + H_2 + Heat$$.
$$\bullet$$ This reaction is an exothermic reaction (a reaction that produce heat).
(ii) 
Magnesium(Mg) metal reacts with hot water to form magnesium hydroxide$$[Mg(OH)_2]$$  and hydrogen gas, but it does not reacts with cold water.
$$\bullet$$  The chemical reaction involved is as follows:
   $$Mg + 2H_2O\rightarrow Mg(OH)_2 + H_2 + Heat$$.
(iii)
 Iron(Fe) metal cannot react with both hot water and cold water. It only reacts with steam, which is water in a gaseous state.
$$\bullet$$  Iron oxide$$(Fe_3O_4)$$ and hydrogen gas$$(H_2)$$ are produced when iron reacts with steam $$(H_2O)$$.
        $$\bullet$$  The chemical reaction involved is as follows:
 $$3Fe+ 4H_2O\rightarrow Fe_3O_4 + 4H_2 + Heat$$.


Based on the following reactions, arrange the metals involved in the following reactions in decreasing order of reactivity:
(i) $$Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$$
(ii) $$Zn + FeSO_4 \rightarrow ZnSO_4 + Fe$$
(iii)$$Cu + 2AgNO_3 \rightarrow Cu(NO_3)_2 + 2Ag $$
(iv) $$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$

 S.No. Reactions Reactivity order reason
 (i)$$Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$$ $$Zn$$ is more reactive than $$Cu$$ $$Zn$$ replace $$Cu$$
 (ii)$$Zn + FeSO_4 \rightarrow ZnSO_4 + Fe$$  $$Zn$$ is more reactive than $$Fe$$  $$Zn$$ replace $$Fe$$
(iii) $$Cu + 2AgNO_3 \rightarrow 2Cu(NO_3)_2 + 2Ag$$  $$Cu$$ is more reactive than $$Ag$$   $$Cu$$ replace $$Ag$$
 (iv) $$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$  $$Fe$$ is more reactive than $$Cu$$  $$Fe$$ replace $$Cu$$

Hence, the order of reactivity is:
$$Zn > Fe > Cu > Ag$$


A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining. Silver articles turn black when kept in the open for a few days because of _________.

Silver articles become black after some time when exposed to air. This is because it reacts with sulphur in the air to form a coating of silver sulphide. This phenomenon is called corrosion of silver.

The original colour and lustre of silver metal are restored by rubbing the surface with toothpaste, as this removes the sulphide layer.

So, the correct answer is corrosion.


What is corrosion? Explain whether gold ornaments corrode or not.

  • The surface of some metals, such as iron, is corroded when they are exposed to moist air for a long period of time. This phenomenon is known as corrosion.
  • Gold ornaments do not get corroded because it is one of the least reactive metals in the reactivity series and it does not react with air or moisture easily. Hence, we can say gold ornaments do not corrode.


Define the reactivity series of metals. 

Reactivity Series is also known as Activity Series. "It is a list of metals arranged in decreasing order of their reactivity". 
Most reactive metals are at the top while the least reactive metals are at the bottom. For any two metals in the series, the metal placed higher in the series can displace lower metals from their salt solution.


Is there any reaction between copper and dilute hydrochloric acid? Give reasons for your answer.

The reactivity of metals is based on the metal reactivity series. The metals placed above hydrogen react with dilute acids to produce salt whereas metals below hydrogen do not react with dilute acids because they are less reactive than hydrogen and therefore they cannot displace hydrogen from dilute acids.

Since copper is placed below hydrogen in the metal reactivity series, therefore it is unreactive and hence it cannot displace hydrogen from dilute hydrochloric acid.


A copper spoon had fallen into a container containing dil. HCl. What would happen to it in three days time?

Copper does not react with dil. HCl, so no reaction would take place. Copper is present below hydrogen in the reactivity series of metals. 


Can you store lemon pickle in an aluminium utensil? Explain.

No, we cannot store lemon pickle in an aluminium utensil because aluminium is a metal and metals readily react with acids to produce hydrogen. When aluminium comes in contact with lemon, which is acidic, would react to give hydrogen and the pickles will be spoiled.


Copper can be extracted by hydrometallurgy but not zinc. Explain.

The reduction potentials of zinc and iron are lower than that of copper. In hydrometallurgy, zinc and iron can be used to displace copper from their solution.

$$Fe(s) + Cu^{2+}(aq)   →   Fe^{2+}(aq)   + Cu(s)$$

But to displace zinc, more reactive metals i.e., metals having lower reduction potentials than zinc such as $$Mg, Ca, K$$, etc. are required. But all these metals react with water with the evolution of $$H_2$$ gas.

$$2K(s)  + 2H_2O (l)   →  2KOH (aq) + H_2(g)$$

As a result, these metals cannot be used in hydrometallurgy to extract zinc.
Hence, copper can be extracted by hydrometallurgy but not zinc.


Ionic compounds are generally soluble in ________.

Answer: water

Ionic compounds are soluble in $$water$$ and insoluble in solvents like petrol and kerosene.


A copper coin is kept immersed in a solution of silver nitrate for some time. What will happen to the coin and the colour of the solution?

(i) A layer of silver metal will be deposited on the copper coin. Silver is below copper in activity series. So, copper being more reactive than silver will displace silver from silver nitrate solution)
(ii) The colour of solution will turn blue because of the formation of copper nitrate solution.


A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument, the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

The man had used the solution of aqua-regia is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of $$1:3$$. On dipping the gold jewellery in the acid solution, the outer layer of gold dissolves and the inner shiny layer appears. This causes a loss in its weight.


Explain why iron sheets are coated with zinc during galvanizing.

Iron when comes in contact with moist air it reacts with it to form a brown powder rust. Rust damages the iron. Thus, to prevent the rusting of the iron they are coated with zinc. 


Why does the colour of copper sulphate change when an iron nail is kept in it? Justify your answer.

Blue colour of copper sulphate solution changes into green colour & then iron nail acquires a brownish look. This is because that iron is more reactive than copper.

$$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$
In this reaction, iron displaces copper from $$CuSO_4$$ solution.


Chemical equation for the reaction between $$CuSO_4$$ solution and an iron nail is given below.
$$CuSO_4 + Fe \rightarrow FeSO_4 + Cu$$
(a) Write the reduction reaction taking place here.
(b) Give reason for the displacement of Cu by Fe from $$CuSO_4$$ solution.

(a) The reduction reaction is as follows:
$$Cu^{2+} + 2e^- \rightarrow Cu$$
(b) Iron comes above copper in the reactivity series, i.e., it can displace copper from the solution.


Name the following:
i) The ion formed by the loss of an electron from its neutral atom
ii) The ion formed by the gain of an electron from its neutral atom
iii) An element that loses an electron to form cation
iv) An element that gains an electron to form an anion
v) Ion(s) involved in the formation of ionic compounds.

i) When an atom loses an electron, it becomes a positively charged ion called a $$\text{cation}$$.
ii) When an atom gains an electron, it becomes negatively charged forming an $$\text{anion}$$.
iii) An $$\text{electropositive}$$ element loses an electron to form a cation. $$Na$$ is one such element, which forms $$Na^+$$ cation.
iv) An $$\text{electronegative}$$ element gains an electron to form an anion. $$Cl$$ is one such element, which forms $$Cl^-$$ anion.
v) Ionic compound is formed by the combination of $$\text{positively & negatively charged ions i.e. cations and anions.}$$


Why are bells made up of metals and not from wood?

Bells are made from metals because metals have the capability to produce sound when hit with a solid object, i.e, they are sonorous. Wood is not sonorous, and is a non-metal.


What is meant by reactivity series of metals?

The series which arranges metals in the decreasing order of reactivity is known as the reactivity series. Thus, the least reactive metal is placed at the bottom while the most reactive metal is placed at the top of the series.
For e.g:- Potassium
                Sodium
                Lithium
                Calcium
                Magnesium
                Zinc 
                Iron
                Copper


Arrange the following metals in the order in which they displace each other from the solution of their salts. 
Al, Cu, Fe, Mg and Zn 

According to activity series, the reactivity order of given metals that displace each other from the solution of their salts is as follows:
$$Mg> Al> Zn> Fe> Cu$$
Here is the complete order, starting with the most reactive metal on the left and proceeding to the least reactive metal on the right:
$$K> Na> Ca> Mg> Al>Zn>Fe>Pb>Cu>Hg>Ag>Au$$


Give an example of a metal which can be easily cut with a knife.

Sodium metal is soft enough to be cut with a knife.
Lithium, potassium are also soft metals that can be easily cut with a knife.


Name two metals which exist in a free state in nature.

The metals that can be found in the free state in nature are gold, silver, platinum. As they are found at the bottom of the activity series and hence are the least reactive metals. Therefore they are found in a free state in nature.


Name the metal which is used to make foils for the packing of food materials.

The metal whose foils are used for the packing of food materials is Aluminium
because aluminum is a soft malleable metal it can be beaten to in sheets to form thin wrapping sheets. 


What is occurrence of metals?

Most metals occur in nature in free state or combined state. A metal is said to occur in free state when it is found in nature in it's metallic form. In combined state, metals occur as compounds with other elements usually non-metallic.


Radha kept milk for curdling in a copper vessel while Priya used steel vessel for the same. Which of the two would be edible and why?

The curd is acidic in nature. As we know the acid attacks most of the metal. If we kept curd in copper and brass it will form a toxic compound harmful for humans. So, we use stainless steel vessels.
When we keep acid (curd) in a copper vessel, they react with each other and produce hydrogen gas and salt. Hydrogen gas is poisonous if combine with metals which is harmful to our body's health.

$$Metal +Acid=Salt+hydrogen\ gas$$



Write chemical equation for the following reaction:

Cinnabar is heated in the presence of air.

Cinnabar is heated in the presence of air:

$$\underset{\left( \text{Cinnabar} \right)}{HgS} + \underset{\left( \text{Air} \right)}{3 {O}_{2}} \xrightarrow[-2 S{O}_{2}]{} 2 HgO \longrightarrow 2 Hg + {O}_{2}$$

When cinnabar (an ore of mercury) is heated in air, it is first converted into mercuric oxide (HgO), which is then reduced to mercury on further heating.


Write balanced chemical equations for each of the following:
(i) Reaction of iron with chlorine.
(ii) Addition of silver nitrate  solution to sodium chloride solution.
(iii) Addition of zinc to sodium hydroxide solution.

$$\text{(i)}$$
$$\bullet$$ When hot Iron (Fe) reacts with chlorine gas ($$Cl_2$$) in a gas jar, iron (III) chloride ($$FeCl_3$$) is formed which is a yellow-brown solid.
$$2Fe + 3Cl_2(g) \rightarrow 2FeCl_3$$

$$\text{(ii)}$$
$$\bullet$$ The addition of a silver nitrate solution to a solution of sodium chloride lead to the formation of a white precipitate.
$$\bullet$$ The white precipitate is produced due to formation of silver chloride, which is insoluble in water.
$$AgNO_3(aq) + NaCl(aq) \rightarrow AgCl(s)  + NaNO_3(aq)$$.

$$\text{(iii)}$$
$$\bullet$$ The compound sodium zincate $$(Na_2ZnO_2)$$, together with hydrogen gas, is formed when zinc reacts with excess sodium hydroxide.
$$Zn + 2NaOH \rightarrow Na_2ZnO_2 + H_2$$


Give balanced chemical equation for the following conversions A,B, and C $$Fe\overset { A }{ \longrightarrow  } Fe{ Cl }_{ 3 }\overset { B }{ \longrightarrow  } FeC{ O }_{ 3 }\overset { C }{ \longrightarrow  } Fe{ \left( { NO }_{ 3 } \right)  }_{ 2 }$$

$$\textbf{Solution-}$$
Following balanced chemical reactions show the conversions
$$\textbf{Part A-}$$ 
By passing chlorine gas $$(Cl_2)$$ over solid iron metal $$(Fe)$$ then ferric chloride $$(FeCl_{3})$$ is produced. 
$$2Fe+3Cl_{2}\rightarrow 2FeCl_{3}$$

$$\textbf{Part B-}$$ 
Ferric chloride $$(FeCl_{3})$$ when reacts with Sodium carbonate $$(Na_2CO_3)$$ it gives Ferrous carbonate $$(Fe_2CO_3)$$ as product
$$FeCl_{3}+Na_2CO_{3}\rightarrow Fe_2(CO_{3})_3$$

$$\textbf{Part C-}$$ 
Ferrous carbonate $$(Fe_2(CO_{3})_3)$$ on reaction with nitric acid $$(HNO_3)$$ produces Ferrous nitrate $$(Fe(NO_3)_2)$$
$$FeCO_{3}+2HNO_{3}\rightarrow Fe\left(NO_{3}\right)_{2}+H_{2}O+CO_{2}$$


The compound $$A$$ is
1396156_a1be15c95ee54d2981c066eadc3a2226.jpg

$$\text{Explanation:}$$
Compound (A) formed after the reaction is $$\text{Metal Chloride}$$
When metal reacts with dilute HCl metal chloride salt and hydrogen gas is produced.
Metal + dil. HCl $$\rightarrow$$ Metal Chloride

For example-  $$2K+H_{2}SO_{4}\rightarrow K_{2}SO_{4}+H_{2}\uparrow$$


Why curd and pickles are not stored in metallic boxes ?

$$\text{Solution-}$$
$$\bullet$$ Curd and Pickles contain lactic acid and acetic acid respectively which are sour in taste. 
$$\bullet$$ Metal boxes are made of brass and copper. If curd or pickle is kept in these boxes, then acid present will react with metal and produce metal salt and hydrogen gas.
                         $$\mathit{Metal + Acid \rightarrow Metal\ Salt + Hydrogen\ gas}$$ 
$$\bullet$$ Toxic substances and hydrogen gas can cause serious health issues or food poisoning. 
$$\bullet$$ Hence, for this reason they are stored in glass or stainless steel containers.


Write a chemical equation for the following reaction.
Zinc metal reacts with aqueous hydrochloric acid to produce a solution of zinc chloride and hydrogen gas.

$$\bullet$$ Zinc metal is a reactive metal which when reacts with dilute hydrochloric acid it produces a solution of zinc chloride and hydrogen gas.
The chemical equation for the reaction is given below.

$$Zn(s)+2HCl(aq)\rightarrow ZnCl_{2}(aq)+H_{2}(g)$$

$$\bullet$$ Hydrogen gas is colorless and odorless gas that burns with a pop sound.


Explain the following giving proper reason:

In moist air, copper objects acquire a green layer on the surface.

Copper reacts with moist air and slowly loses its shiny brown surface and gains a green coat (or another colour depending on which component of air it reacts with). This green outer layer is also called patina. The process is called corrosion, which occurs when a metal is attacked by substances around it such as air, moisture, acids, etc.


You are given samples of three metals - sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivities.

(i) When sodium, magnesium and copper are left in air, sodium reacts vigorously with oxygen to form sodium oxide, magnesium reacts with oxygen to form magnesium oxide only on heating, whereas copper does not burn in air even on string heating. It reacts only on prolonged heating. This shows that sodium is most reactive, then magnesium and copper are the least reactive among the three.

(ii) Sodium reacts vigorously with cold water to form sodium hydroxide and hydrogen, magnesium does not react with cold water but reacts with hot water to form magnesium hydroxide and hydrogen but copper does not react even with steam. This shows that sodium is highly reactive, magnesium is less reactive than sodium and copper is the least reactive among the three.


What is the action of water on (a) sodium (b) magnesium and (c) aluminium? Write the equations of the chemical reactions involved.

(a) Sodium reacts vigorously with cold water forming sodium hydroxide and hydrogen gas. 

Reaction: $$ 2Na(s) + 2H_2O(l)  \rightarrow 2NaOH (aq) +H_2(g) + heat $$

(b) Magnesium reacts with hot water to form magnesium hydroxide and hydrogen. 

Reaction: $$ Mg(s) +2H_2O(l) \rightarrow Mg(OH)_2(aq) + H_2(g) $$

(c) Aluminium reacts with steam to form aluminium oxide and hydrogen gas.

Reaction: $$ 2Al(s) + 3H_2O(g)  \rightarrow Al_2O_3 (s) + 3H_2(g) $$


Name the metal which has been placed : 
(a) at the bottom of the reactivity series. 
(b) at the top of the reactivity series. 
(c) just below copper in the reactivity series.

The reactivity series follows the order:
$$K>Na>Ca>Mg>Al>C>Zn>Fe>Sn>Pb>H>Cu>Hg>Ag>Au$$
(a) The metal which has been placed at the bottom of the reactivity series is gold.
(b) The metal which has been placed at the top of the reactivity series is potassium.
(c) The metal which has been placed just below copper in the reactivity series is mercury.


Name the non-metal which is used :
(a) To convert vegetable oil into vegetable ghee(solid fat) 
(b) As a rocket fuel (in liquid form)
(c) To preserve food materials

(a) Hydrogen is the non-metal which is used to convert vegetable oil into vegetable ghee (solid fat).

(b) Hydrogen is the non-metal which is used as a rocket fuel (in liquid form).

(c) Nitrogen is the non-metal which is used to preserve food materials.



(a) Name the most abundant metal in the earth's crust.
(b) Name the most abundant non-metal in the earth's crust.

(a) The most abundant metal present in the earth's crust is Aluminium.

(b) The most abundant non-metal present in the earth's crust is Oxygen.


(a) What is meant by the reactivity series of metals? Arrange the following metals in an increasing order of their activities towards water.
Zinc, iron, magnesium, Sodium
(b) Name one metal more reactive and another less reactive than hydrogen.
(c) Name one metal which displaces copper from copper sulphate solution and one which does not.
(d) Name one metal which displaces silver from silver nitrate solution and one which does not.

(a) The arrangement of metals in a vertical column in the order of decreasing reactivities is called reactivity series. The reactivity series follows the order:
$$K>Na>Ca>Mg>Al>Zn>Fe>Pb>H>Cu>Hg>Ag>Au$$
(b) Lead is more reactive than hydrogen and copper is less reactive than hydrogen
(c) Zinc displaces copper from copper sulphate solution and mercury does not displace copper from copper sulphate solution 
(d) Copper displaces silver from silver nitrate solution and gold does not.


How would you show that silver is chemically less reactive than copper ?

If a strip of silver metal is kept immersed in copper sulphate solution for some time, then no reaction occurs. This shows that silver is not able to displace copper from copper sulphate solution as it is less reactive than copper.

$$Ag+CuSO_4\rightarrow$$ No reaction.


What is meant by "brittleness"?  Which type of elements usually show brittleness: metals or non-metals?

Brittleness is the property of being brittle i.e. breaking easily. Non-metal shows brittleness. 


Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except $$Mn$$ and $$Mg$$), treated with $$HNO_3$$, hydrogen is not liberated, why?

Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because $$HNO_3$$ is a strong oxidising agent. It oxidises the $$H_2$$ produced to water and itself gets reduced to any of the nitrogen oxides ($$N_2O, \ NO, \ NO_2$$). 


Name two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved if any during the reaction?

Sodium and potassium metals react violently with cold water. 

Observations :
1. Metal starts moving over the surface of the water making a hissing sound.
2. Metal starts reacting with water causing little explosion
3. Soon the metal catches fire and starts burning.

Reaction:
$$2K+2H_2O\rightarrow 2KOH+H_2$$
$$2Na+2H_2O\rightarrow 2NaOH+H_2$$

The gas evolved during the reaction can be identified by bringing a burning candle near it. The candle burns with a pop sound indicating the evolution of hydrogen gas.


In a solution of lead acetate, a strip of metal M was dipped, after sometime lead from the solution was deposited on the metal strip. Which metal is more reactive M or lead?

M is more reactive than lead since it is able to displace lead from lead acetate solution.

Reaction: $$PbC_2O_4+M\rightarrow MC_2O_4+Pb.$$


A student has found black coating on his silver coins and green coating on his copper coins. Which chemical phenomenon is responsible for this? Write the chemical name of these coatings.

The chemical phenomenon which is responsible is $$\text{corrosion}$$.
When a metal is attacked by substances around it such as moisture, acids, etc. it is said to be corroded and this process is called corrosion.
After corrosion, the color of:
$$\text{Silver coints changes to}$$ $$\rightarrow$$ $$black$$
$$\text{Copper coins changes to}$$ $$\rightarrow $$ $$green$$

the chemical name of black coating is $$\text{silver sulphide}$$ which is formed by the reaction of silver coin with atmospheric sulphur and green coating is of $$\text{copper carbonate}$$ which is formed due to the reaction of copper with moist carbon dioxide from the air.


(a) Name a metal for each case:
     (i) It does not react with cold and hot water but reacts with steam.
     (ii) It does not react with water.
(b) When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on addition of sodium metal to water catches fire. Why is it so?

(a) (i) Iron metal does not react with cold as well as hot water but reacts with steam.

(a) (ii) Metals such as lead, copper, silver and gold do not react with water at all.

(b) More heat is evolved during the reaction of sodium metal with water due to which the hydrogen gas formed catches fire. On the other hand, less heat is evolved during the reaction of calcium metal with water which cannot make hydrogen gas burn.


Name any three objects (or structures ) which are gradually damaged by the corrosion of iron and steel.

Three objects (or structures ) that are gradually damaged by the corrosion of iron and steel are railings, car bodies, and bridges.


What do you mean by malleability and ductility of a metal ?

Malleability is the property of metal to be hammered into thin sheets. 
Ductility is the property to enable metals to be drawn into wires.


How are highly reactive metals reduced?

Highly reactive metals (e.g., sodium-potassium ) are reduced from their compounds by electrolytic reduction. By electrolysing the chlorides or oxides of these metals, the pure metal is deposited at the cathode. 


Name two metals that do not react with water at all.

Answer: 
  1. Lead
  2. Copper
Metals such as lead, copper, silver and gold do not react with hot/cold water or steam.


What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails dipped in copper sulphate solution for about $$30$$ minutes?

Iron nails become brownish in colour and the blue colour of copper sulphate solution disappears. This is because iron displaces copper from copper sulphate solution and forms ferrous sulphate which has a pale green colour.
reaction,
$$\underset{blue\ colour}{CuSO_{{4}{(aq)}}} +  Fe_{(s)} \longrightarrow  \underset {pale\ green}{FeSO_{{4}{(aq)}}} +  Cu_{(s)}$$
Iron is more reactive than copper and hence it can displace copper from it's solution.


How are metals which are in the middle of the reactivity series reduced? 

Metals that come in the middle of the reactivity series are reduced from their compound using any of the following techniques. 

i. If the compound is a metal oxide, then it is reduced to the corresponding metals by reducing using carbon(coke) in the presence of heat. 

ii. If the compound is a metal carbonate, then it is converted into ore corresponding to the metal oxide by strongly heating it in the limited air (calcination). Later, metals oxides are reduced to metals using carbon. 

iii. If the compound is a metal sulphide, then it is converted into corresponding metal oxide by strongly heating it in excess air (roasting). Then the metal oxide obtained is reduced to metal using carbon. 


Given reasons why :
(a) Copper metal is used for making electric wires.
(b) Gold and Silver is used for making jewellery

(a) Copper can be used for making electric wires because it is cheap, ductile in nature and has high electrical conductivity.
(b) Since Gold and Silver are also metals, they are malleable, ductile, have high value and also have a shiny lustre which makes them appropriate for making jewellery.


What happens when calcium is treated with water?

Calcium metal begins to bubble vigorously as it reacts with the water, producing hydrogen gas, it starts floating because the bubbles of hydrogen gas formed stick to the surface of the metal.
$$Ca + H_2O \rightarrow Ca(OH)_2+ H_2$$


During extraction of metal, electrolytic refining is used to obtain pure metals.
Suggest a suitable electrolyte also.

Electrolyte : Silver salt, such as $$AgNO_{3}, AgCl,$$ etc.


When calcium metal is added to water the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so?

In both cases, the hydrogen gas ($$H_{2}$$) is evolved is. When calcium reacts with water the heat evolved is not sufficient for hydrogen to catch fire. On the other hand, sodium metal reacts with water violently and in this case, a lot of heat is evolved which is sufficient for hydrogen to catch fire.


During extraction of metals, electrolytic refining is used to obtain pure metals. 
(a) Which material will be used as anode and cathode for refining of silver metal by this process? 
(b) Suggest a suitable electrolyte also.
(c) In this electrolytic cell, where do we get pure silver after passing electric current? 

(a) During electrolytic refining, impure metal is used as anode and pure metal is used as cathode. So. impure silver will be used as anode and pure silver will be used as cathode. 
(b) Silver sulphate or Silver nitrate solution can be a suitable electrolyte. 
(c) Pure silver will be obtained on cathode; because metals are electropositive.


Paheli prepared a blue coloured solution of copper sulphate in beaker A and placed an iron nail in it. Boojho prepared a yellowish green solution of ferrous sulphate in beaker B and placed a copper wire in it. What changes will they observe in the two beakers after an hour?

Iron is more reactive than Copper and thus it displaces Copper from its salt solution. In beaker A, Copper's reddish brown layer will deposit on the iron nail and copper sulphate's blue colour solution will become yellowish green because this process forms Iron sulphate. In beker B, There's no change because the less reactive property of copper doesn't be able to displace iron from ferrous sulphate solution.


Iqbal treated lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions. 

Burning matchstick should be brought near the evolved gas. If matchstick burns with a pop sound. it indicates evolution of hydrogen gas.
Reaction with $$NaOH$$:
$$M + 2NaOH \rightarrow Na_2MO_2 + H_2$$
Reaction with $$HCl$$:
$$M + 2HCl \rightarrow MCl_2 + H_2$$


During the reaction of some metals with dilute hydrochloric acid, following observations were made.
(a) Silver metal does not show any change
(b) The temperature of the reaction mixture rises when aluminium (Al) is added.
(c) The reaction of sodium metal is found to be highly explosive
(d) Some bubbles of gas are seen when lead (Pb) is reacted with the acid.
Explain these observations giving suitable reasons.

(a) Silver metal does not react with dilute HCl because silver lies low in the reactivity series of metal

(b) The temperature of the reaction mixture rises when aluminium is added because it is an exothermic reaction.

(c) The reaction of sodium metal is found to be highly explosive because Sodium is highly reactive thus resulting in an exothermic reaction which lead to an increase in temperature. 

(d) When lead is treated with hydrochloric acid, bubbles of hydrogen gas are evolved.
$$P b+2 H C l \rightarrow P b C l_{2}+H_{2}$$


 Properties of the elements arc given below. Where would you locate the following elements in the periodic table?
(a) A soft metal stored under kerosene 
(b) An element with variable (more than one) valency stored under water. 
(c) An element which is tetravalent and forms the basis of organic chemistry 
(d) An element which is an inert gas with atomic number
(e) An element whose thin oxide layer is used to make other elements corrosion resistant by the process of "anodising" 

(a) Sodium Group 1, Period 3 
(b) Phosphorus Group 15, Period 3
(c) Carbon Group 14, Period 2
(d) Helium Group 18, Period 1
(e) Aluminum Group 13, Period 3  


Name a metal that can be cut with knife. 

Sodium is a metal that can be cut with a knife. It is a very soft metal.


Explain the following
(a) Reactivity of Al decreases if it is dipped in $$HNO_3$$. 
(b) Carbon cannot reduce the oxides of Na or Mg.
(c) $$NaCl$$ is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.
(d) Iron articles are galvanised.
 (e) Metals like Na, K, Ca and Mg are never found in their free state in nature. 

(a) Nitric acid is a strong oxidizing agent. Due to this, when aluminium is dipped in nitric acid, a layer of aluminium oxide is deposited on aluminium. As a result; reactivity of aluminium decreases when it is dipped in nitric acid. 
(b) Sodium and magnesium are highly reactive metals. Hence, they have higher affinity to oxygen than to carbon. Due to this, carbon fails to reduce the oxides of sodium or magnesium.
(c) $$NaCl$$ is an ionic compound. Ionic compounds do not conduct electricity in solid state. But ionic compounds are good conductors of electricity in molten state and in aqueous solution. 
(d) Iron has a tendency to react with atmospheric moisture. This process is called rusting and leads to corrosion of iron. Iron articles are galvanized to prevent rusting of iron.
(e) Na, K. Ca and Mg are highly reactive metals. They can easily form compound with most of the elements. Due to this, these metals are not found in their free state in nature.


Non-metals are usually poor conductors of heat and electricity. They are non- lustrous, non-sonorous, non-malleable and are coloured. Name a non-metal other than carbon which shows allotropy.

Sulphur, phosphorus shows allotropy.


Out of non-metals and metals, which is hard, ductile, sonorous and malleable?

Metals are hard, ductile, sonorous, and malleable.
Non-metals are not ductile because they are brittle elements. They break easily. Such non-metals cannot be deformed by a hammer or rolling.


Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements. 
(a) $$Mg$$ and $$N_2$$
(b) $$Li$$ and $$O_2$$
(c) $$Al$$ and $$Cl_2$$
(d) $$K$$ and $$O_2$$

(a) Magnesium nitride $$(Mg_3N_2)$$
(b) Lithium oxide $$(Li_2O)$$
(c) Aluminium chloride $$(AlCl_3)$$
(d) Potassium oxide $$(K_2O)$$


What is the sheet used for roofing made from? Why?

Aluminium is used to make sheets for roofing because it is malleable i.e. it can be hammered into sheets.


Name a non-metal that is hardest naturally occurring substance. 

Diamond (an allotrope of Carbon) is a non-metal which is the hardest naturally occurring substance. 


Under what condition iron reacts with water.

Iron does not react with water directly. Red hot iron reacts with steam :-
$$3Fe(s) + 4H_2O(g) → Fe_3O_4(s) + 4H_2(g)$$


Name the following:
(a) A non-metal that is lustrous.
(b) A metal that is liquid at room temperature.
(c) An allotrope of carbon that conducts electricity.
(d) An alkali metal that can be cut with a knife.

(a) Iodine is a lustrous non-metal. Most other non-metals are non-lustrous. Lustre is a property mainly of metals.
(b) Mercury is the only metal that is liquid at room temperature. 
(c) Graphite is a non-metal and is an allotrope of carbon that conducts electricity. Conduction of electricity is mostly a property of metals.
(d) Sodium is an alkali metal that is so soft that it can be cut with a knife. Most other metals are strong and tough.


What is corrosion? What are the necessary conditions for corrosion?

When the surface of a metal is attacked by air and moisture, the metal is said to corrode and the phenomenon is known as corrosion.
Necessary conditions for corrosion are:
- Presence of moisture i.e, air and water


Complete and balance the following equation.
$$Na+H_2O \to --+---$$

Metals react with water and produce a metal oxide and hydrogen
gas. Metal oxides that are soluble in water, dissolve in it to further form
metal hydroxide.
$$2Na +2H_2O \to 2NaOH+H_2$$


Which gas is bubbled on the surface of sodium metal?

Metals react with water and produce a metal oxide and hydrogen gas.
That is why we can say hydrogen gas is bubbled on the surface of sodium metal when sodium metal reacts with water.


Aluminum utensils are used for cooking. Which property of aluminum is used?

The properties of aluminum for which aluminum utensils are used for cooking are good thermal conductivity, malleability, lightweight, and high melting point.


What is a screwdriver made from? Why? 

A screwdriver is made up of steel which consists of iron. Since Iron is a metal, it is hard and durable that suits the purpose of a screwdriver.


Write products of reaction of acid with metal.

When an acid reacts with a metal, the corresponding salt of the metal and hydrogen gas are formed.

 Acid   +   Metal $$\rightarrow$$ Salt of Metal  +  Hydrogen gas.
$$2HCl$$ + $$ Mg$$  $$\rightarrow$$  $$MgCl_2$$  +  $$H_2$$


Differentiate between metals and non-metals on the basis of their physical properties.

$$\text{Physical properties of metal }$$ :

1. $$State$$: Most of the metals are found in a solid state at normal temperature except mercury $$ (Hg) $$which is found in a liquid state at normal temperature.

2. $$Lustre$$: Most of the metals are lustrous such as gold, silver, copper, aluminium.

3. $$Sonorous$$: Most of the metals, when struck with other hard metals or objects, produce a special sound. Due to this property of metals they are used to manufacture bell and music instrument etc.

4. $$ Melting\ point$$: Melting points of metals are generally high except galium and caesium which have low melting points.

5.  $$Heat\ conductivity$$: Metals are generally good conductors of heat. This is the reason that cooking utensils are made of metals.

6. $$Malleability$$: Metals can be converted into thin sheets by hammering, thus they are malleable.

7. $$Ductility $$: Metals can be converted into wires. This property of metals is called ductility.

8. $$Electricity$$ $$conductivity$$ : Metals allow electricity to pass through them. this property is called conductivity of electricity. Silver is the best conductor is electricity. 

$$\text{Physical properties of  Non-metals}$$ :

1. $$Physical$$ $$state$$ : They are found three states i.e. solid , liquid and gas at normal  temperature such as -solid carbon $$(C) $$ , sulphur $$ (S) $$ , iodine $$ (I) $$, liquid -bromine $$ (Br) $$ and gas oxygen $$ (O_2) $$, nitrogen $$ (N_2) $$, hydrogen $$ (H_2) $

2. $$Lustre$$ : Non-metals are non lustrous .Iodine is an exception, it is a lustrous non-metal.

3.$$ Hardness $$: They are soft. Diamond is an exception, it is the hardest nonmetals found on earth.

4. $$Sonorous$$:  They do not produce sound.

5.$$\text{ Melting point  }$$: They have a low melting point except for diamond and graphite . Diamond and graphite (allotropes of carbon) have a very high melting point.

6.$$\text{ Heat and electric conductivity}$$: They are bad conductors of heat and electricity except for graphite, which is a good conductor of electricity.

7.$$ Brittle$$: They break into pieces when beaten with a hammer, thus they are brittle.


Which are the metals found in free state? Why?

Metals like gold, platinum, silver, copper etc. are found in free state,. because these metals do not react with air.


Name two metals which react with cold water.

Potassium & Sodium are two metals which react with cold water.


How many of the following substances do not shine?
Sulphur, Copper, Diamond, Lead, and Iodine

As a general rule, metals are lustrous and non-metals are non lustrous. However, there are exceptions, carbon in the form of diamond shines and so does iodine. So, among the above substances, sulphur and lead are non-lustrous. So, the correct answer is 2.


Some properties are listed in the following table. Distinguish between metals and non-metals based on these properties.
PropertiesMetalsNon-metals
Appearance
Hardness
Malleability
Ductility
Heat Conduction
Conduction of Electricity

 Properties Metals Non-metals
 1. Appearance Lustrous Dull
 2. Hardness Hard Soft
 3. Malleability Malleable Non-malleable
 4. Ductility Ductile Non-ductile
 5. Heat conduction Good Bad
 6. Conduction of electricity Good Bad


Write the difference between metals and non-metals under the following heads.
(i) Nature, (ii) State, (iii) Lustre, (iv) Ductility, (v) Malleability, (vi) Conductivity

  MetalsNon-metals
(i) NatureThey are hard.
They are soft (except diamond).
(ii) StateThey are solids at room temperature (except mercury which is liquid).
They are either solids, or liquids or gases.
(iii) LustreMetals are lustrous. They have shiny surfaces.
Metals are non-lustrous (except iodine).
(iv) DuctilityThey are ductile. They can be converted into thin wires.
They are non ductile.
(v) MalleabilityThey are malleable. They can be converted into thin sheets by hammering (sodium and potassium are exceptions).
They are brittle. They will break down into pieces when beaten by hammer.
(vi) Conductivity
They are good electrical and thermal conductors.
They are poor electrical and thermal conductors (except graphite).


Explain the principle of the method of electrolytic refining of metals by giving an example.

Principle of the method of Electrolytic refining-
Electrolytic refining is the method of using electricity to refine impure metals. In this process, the anode is made of impure metal, and the cathode is made of a strip of pure metal. A solution is made with a soluble salt of the same substance as the electrolyte. When an electric current is transmitted, metal ions from the electrolyte are deposited as a pure metal in the cathode, and the impure metal from the anode dissolves in the form of ions into the electrolyte. Below the anode, the impurities metals are collected. It is called mud anode. In the electrolytic refining of copper, the electrolyte is a solution of acidified copper sulphate. The anode is impure copper, whereas the cathode is a strip of pure copper on passing electric current, pure copper is deposited on the cathode.


One day Reeta went to a jeweler's shop with her mother. Her mother gave old gold jewelry to the goldsmith to polish. The next day when they brought the jewelry back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss of weight?

Hint: Gold is an inert metal and requires a harsh condition to dissolve.

Explanation:
  • The most common method that goldsmiths used to polish is to dissolve gold in suitable solvent and then make it shiner.
  • As Gold is an inert metal only aqua regia is able to dissolve it.
  • Aqua regia is the only combination of strong acids which can dissolve gold easily as shown below:
      
  • $$1:3$$ ratio of $$HNO_{3}$$ and $$HCl$$ known as aqua regia.
  • When gold is dissolved in aqua regia, the outer layer of gold dissolves and a shiny inner layer shows.
  • So, the weight of the jewellery is reduced due to the layer’s dissolution. 

    Final Answer: Loss of weight of gold jewelry is due to dissolution of the outer layer of jewelry by aqua regia.


How electrolytic refining a copper is carried out ? Explain in detail . 

The electrolytic refining of copper is done using the apparatus shown in the figure. 
This is a standard electrolysis setup, where the impure copper (the sample to be refined) is placed as anode and a thin strip of pure copper is placed as a cathode. The electrolyte used is copper sulfate solution. When current is passed through the electrolyte pure copper content from the anode dissolves into the electrolyte, and the same amount of copper is deposited on the cathode. One can see that the thickness of the cathode increases. The soluble impurities present in the anode gas into the solution when the current flows through the setup. The insoluble impurities present in the anode settle down electrolytically. 

1625402_1772703_ans_c3f95fd70d7040a5b3ba2bec19ddb032.png


A copper coin was kept dipped in silver nitrate solution for a few hours/days. What will happen to the copper coin? What will happen to the colour of the solution?

Copper metal is more reactive than silver metal thus when a copper coin is kept immersed in silver nitrate solution for some time, it displaces silver from silver nitrate solution.

The reaction is :

$$\mathrm{Cu+2AgNO_3 \rightarrow Cu(NO_3)_2 +2Ag}$$

The grey solid crystal of Ag metal are seen growing on the copper coin and the solution turns blue in colour due to the formation of cupric nitrate.



What happens when zinc granules are treated with dilute solution of $$H_{2} SO_{4}$$, $$HCl$$, $$HNO_{3}$$, $$NaCl$$ and $$NaOH$$? Also write the chemical equations if reaction occurs.

The reaction of Zn granules with

(a) Dilute  $$H_{2} SO_{4}$$
$$Z n(s)+H_{2} S O_{4}(a q) \rightarrow Z n S O_{4}(a q)+H_{2}(g)$$

(b) Dilute HCl
$$Z n(s)+2 H C l(a q) \rightarrow Z n C l_{2}(a q)+H_{2}(g)$$

(c) Dilute  $$HNO_{3}$$
Reaction with dilute $$H N O_{3}$$ is different as compared to other acids because nitric acid is an oxidising agent and it oxidises $$H_{2}$$ gas evolved to $$H_{2} O$$
$$4 Z n(s)+10 H N O_{3}(a q) \rightarrow 4 Z n\left(N O_{3}\right)_{2}(a q)+5 H_{2} O(I)+N_{2} O(g)$$

(d) $$NaCl$$ solution
$$Z n(s)+N a C l(a q) \rightarrow$$ No reaction

(e) $$NaOH$$ solution
$$Z n(s)+2 N a O H(a q) \rightarrow N a_{2} Z n O_{2}(a q)+H_{2}(g)$$


Take water in $$4$$ different beakers and add a small piece of sodium, lead, iron and copper in each.
In which solution, gas bubbles will be formed? Which gas is formed?

Sodium is a very reactive metal and the reaction is so violent and exothermic that the evolved hydrogen immediately catches fire. Calcium also reacts with water however, the reaction of calcium with water is less violent. The heat evolved is not sufficient for the hydrogen to catch fire. Calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the metal. Gas bubbles are formed in the beaker containing Calcium & Sodium. 

Hydrogen gas is formed.

$$2Ca +2H_2O\rightarrow 2Ca(OH)_2 +H_2$$
$$2CN +2H_2O\rightarrow 2NaOH +H_2$$


Which metal reacts with hot water? Which gas will be produced? Write the chemical equation.

Magnesium is the metal that reacts with hot water and on the reaction the gas released is Hydrogen.

Reaction: $$Mg+H_{2}O\rightarrow MgO+H_{2}$$


Class 10 Chemistry Extra Questions