Chapter 3: Metals and Non-metals

Multiple Choice Questions

1. Which of the following property is generally not shown by metals?

(a) Electrical conduction    (b) Sonorous in nature    (c) Dullness    (d) Ductility

Answer : (c) Dullness

[ Metals are generally lustrous (shiny), so dullness is not a common property of metals.]

2. The ability of metals to be drawn into thin wire is known as

(a) ductility     (b) malleability    (c) sonorousity    (d) conductivity

Answer : (a) ductility

[ Ductility is the property of metals by which they can be drawn into thin wires.]

3. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?

(i) Good thermal conductivity    (ii) Good electrical conductivity   (iii) Ductility    (iv) High melting point

(a) (i) and (ii)     (b) (i) and (iii)    (c) (ii) and (iii)    (d) (i) and (iv)

Answer :  (a) (i) and (ii)

[ Aluminium is used for cooking utensils due to its good thermal conductivity and high melting point .]

4. Which one of the following metals do not react with cold as well as hot water?

(a) Na           (b) Ca          (c) Mg           (d) Fe

Answer : (d) Fe (Iron).

[ Iron (Fe) does not react with cold or hot water. While it can react with steam to form iron oxide and hydrogen gas ]

5. Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

(a) FeO           (b)          (c)    (d)  and  

Answer :  (c)

[ The reaction is  ]

6. What happens when calcium is treated with water?

(i) It does not react with water

(ii) It reacts violently with water

(iii) It reacts less violently with water

(iv) Bubbles of hydrogen gas formed stick to the surface of calcium

(a) (i) and (iv)      (b) (ii) and (iii)      (c) (i) and (ii)       (d) (iii) and (iv)

Answer :  (d) (iii) and (iv).

[ When calcium is treated with water, it reacts to produce calcium hydroxide and hydrogen gas.

The reaction is   ]

7. Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?

(a)      (b) HCl     (c)       (d) All of these

Answer : (c)

[Nitric acid is a strong oxidizing agent, and when it reacts with metals, it tends to oxidize them and itself undergoes reduction, resulting in the formation of nitrogen oxides and not hydrogen gas. ]

8. The composition of aqua-regia is

(a) Dil.HCl : Conc.

             3 : 1

(b) Conc.HCl : Dil.

                 3 : 1

(c) Conc.HCl : Conc.

                3 : 1

(d) Dil.HCl : Dil.  

             3 : 1

Answer :  (c) Conc.HCl : Conc.

                                3 : 1

[(c) Conc. HCl : Conc. HNO₃ = 3 : 1 . Aqua-regia is a mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio 3:1.]

9. Which of the following are not ionic compounds?

(i) KCl      (ii) HCl       (iii)       (iv) NaCl

(a) (i) and (ii)     (b) (ii) and (iii)     (c) (iii) and (iv)   (d) (i) and (iii)

Answer :  (b) (ii) and (iii).

[ HCl (hydrochloric acid) is a covalent compound, not an ionic compound. It is formed by the combination of hydrogen (a non-metal) and chlorine (a non-metal).  (carbon tetrachloride) is also a covalent compound. It consists of carbon (a non-metal) and four chlorine atoms (non-metals) bonded covalently. ]

10. Which one of the following properties is not generally exhibited by ionic compounds?

(a) Solubility in water

(b) Electrical conductivity in solid state

(c) High melting and boiling points

(d) Electrical conductivity in molten state

Answer :  (b) Electrical conductivity in solid state

 [ Ionic compounds exhibit electrical conductivity in the molten state or in aqueous solutions.]

11. Which of the following metals exist in their native state in nature?

(i) Cu        (ii) Au        (iii) Zn        (iv) Ag

(a) (i) and (ii)         (b) (ii) and (iii)       (c) (ii) and (iv)        (d) (iii) and (iv)

Answer : (c) (ii) and (iv)

[ (c) (ii) and (iv) . Gold and Silver occur in native state because they are less reactive metals.]

12. Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?

(i) Au         (ii) Cu        (iii) Na       (iv) K

(a) (i) and (ii)      (b) (i) and (iii)     (c) (ii) and (iii)     (d) (iii) and (iv)

Answer :  (a) (i) and (ii):

[ Gold (Au) and copper (Cu) are both refined by electrolytic refining, a process that involves passing an electric current through a solution containing ions of the metal to be refined, and the metal is deposited at the cathode. ]

13. Silver articles become black on prolonged exposure to air. This is due to the formation of

(a)      (b)      (c)       (d)  and

Answer: (c) 

[ The blackening of silver articles on prolonged exposure to air is due to the formation of a thin layer of silver sulphide (). ]

14. Galvanisation is a method of protecting iron from rusting by coating with a thin layer of

(a) Gallium     (b) Aluminium    (c) Zinc    (d) Silver

Answer: (c) Zinc

[Galvanization is a method of protecting iron from rusting by coating it with a thin layer of zinc. ]

15. Stainless steel is very useful material for our life. In stainless steel, iron is mixed with

(a) Ni and Cr     (b) Cu and Cr      (c) Ni and Cu    (d) Cu and Au

Answer : (a) Ni and Cr

[ (a) Ni and Cr . Stainless steel is made by mixing iron with Nickel and Chromium to prevent rusting.]

16. If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of

(a)      (b)       (c)       (d) CuO

Answer : (d) CuO

[ If copper is exposed to air, it reacts with oxygen and moisture to form copper oxide. The green coating that forms on the surface of copper is primarily composed of copper(II) oxide (CuO). ]

17. Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?

(a) Na     (b) Fe     (c) Cr      (d) Hg

Answer: (d) Hg

[ The metal that is found in a liquid state at room temperature is mercury (Hg). ]

18. Which of the following metals are obtained by electrolysis of their chlorides in molten state ?

(i) Na      (ii) Ca      (iii) Fe     (iv) Cu

(a) (i) and (iv)       (b) (iii) and (iv)        (c) (i) and (iii)      (d) (i) and (ii)

Answer : (d) (i) and (ii)

[ The metals obtained by electrolysis of their chlorides in molten state are sodium (Na) and calcium (Ca). ]

19. Generally, non-metals are not lustrous. Which of the following non- metal is lustrous?

(a) Sulphur        (b) Oxygen      (c) Nitrogen       (d) Iodine

Answer : (d) Iodine

[ Iodine is a non-metal that is lustrous. Iodine has a shiny appearance, especially when it is in the form of crystals. ]

20. Which one of the following four metals would be displaced from the solution of its salts by other three metals?

(a) Mg          (b) Ag      (c) Zn           (d) Cu

Answer : (b) Ag (Silver).

[ Silver is less reactive than magnesium (Mg), zinc (Zn), and copper (Cu). Therefore, magnesium, zinc, and copper can displace silver from the solution of its salts.]

21. 2 mL each of concentrated HCl,  and a mixture of concentrated HCl and concentrated   in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put ineach test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be

(a) Al      (b) Au       (c) Cu     (d) Pt

Answer : (b) Au.

[ Aqua regia is known for its ability to dissolve noble metals like gold (Au) and platinum (Pt). Gold (Au) is a noble metal that can be dissolved by aqua regia. ]

22. An alloy is

(a) an element        (b) a compound     (c) a homogeneous mixture        (d) a heterogeneous mixture

Answer :  (c) homogeneous mixture.

[ An alloy is a mixture of two or more elements, at least one of which is a metal. ]

23. An electrolytic cell consists of

(i) positively charged cathode         (ii) negatively charged anode

(iii) positively charged anode          (iv) negatively charged cathode

(a) (i) and (ii)         (b) (iii) and (iv)       (c) (i) and (iii)         (d) (ii) ad (iv)

Answer : (b) (iii) and (iv)

[ In an electrolytic cell:  The cathode is negatively charged and the anode is positively charged. ]

24. During electrolytic refining of zinc, it gets

(a) deposited on cathode      (b) deposited on anode      (c) deposited on cathode as well as anode       (d) remains in the solution

Answer : (a) deposited on cathode

[ During the electrolytic refining of zinc, zinc is deposited on the cathode. ]

25. An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following

(a) Mg           (b) Na         (c) P             (d) Ca

Answer : (b) Na

[ The element described as soft, reacting vigorously with water, and being very reactive to air is most likely sodium (Na). ]

26. Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?

(a) Brass        (b) Bronze      (c) Amalgam    (d) Steel

Answer :  (d) Steel

[ Steel is an alloy of iron (a metal) and carbon (a non-metal). Therefore, steel is the alloy that contains a non-metal as one of its constituents. ]

27. Which among the following statements is incorrect for magnesium metal ?

(a) It burns in oxygen with a dazzling white flame

(b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas

(c) It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas

(d) It reacts with steam to form magnesium hydroxide and evolves hydrogen gas

Answer :  (b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas.

[ Magnesium does not react vigorously with cold water. Instead, it reacts slowly with hot water or steam to form magnesium oxide and evolves hydrogen gas. ]

28. Which among the following alloys contain mercury as one of its constituents?

(a) Stainless steel    (b) Alnico     (c) Solder      (d) Zinc amalgam

Answer : (d) Zinc amalgam

[ The alloy that contains mercury as one of its constituents is zinc amalgam .]

29. Reaction between X and Y, forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?

(a) Has high melting point       (b) Has low melting point      (c) Conducts electricity in molten state       (d) Occurs as solid

Answer :  (b) Has low melting point

[ Ionic compounds typically have high melting and boiling points due to the strong electrostatic forces between oppositely charged ions. Therefore, the property not shown by Z would be having a low melting point. Ionic compounds tend to be solids at room temperature with high melting points.]

30. The electronic configurations of three elements X, Y and Z are X – 2.8; Y – 2.8.7 and Z – 2.8.2. Which of the following is correct?

(a) X is a metal       (b) Y is a metal      (c) Z is a non-metal    (d) Y is a non-metal and Z is a metal

Answer : (d) Y is a non-metal and Z is a metal     

[ The electronic configurations provided are:

X: 2.8 ; Y: 2.8.7  ; Z : 2.8.2

X has 2 electrons in the outermost shell, suggesting it is a metal.

Y has 7 electrons in the outermost shell, suggesting it is a non-metal.

Z has 2 electrons in the outermost shell, suggesting it is a metal. ]

31. Although metals form basic oxides, which of the following metals form an amphoteric oxide?

(a) Na    (b) Ca      (c) Al     (d) Cu

Answer : (c) Al

[ An amphoteric oxide is one that can act as both an acid and a base. Among the options provided, aluminum (Al) forms an amphoteric oxide. ]

32. Generally, non-metals are not conductors of electricity. Which of the following is a good conductor of electricity?

(a) Diamond     (b) Graphite      (c) Sulphur       (d) Fullerene

Answer : (b) Graphite.

[ Graphite is a good conductor of electricity. Graphite is a form of carbon with a unique structure that allows electrons to move freely, making it a good conductor. ]

33. Electrical wires have a coating of an insulting material. The material, generally used is

(a) Sulphur       (b) Graphite      (c) PVC       (d) All can be used

Answer : (c) PVC

[ Electrical wires are typically coated with an insulating material to prevent the flow of electric current and to ensure the safety of the wiring.  PVC (Polyvinyl chloride) is a common insulating material used for electrical wires.]

34. Which of the following non-metals is a liquid?

(a) Carbon      (b) Bromine     (c) Phosphorus      (d) Sulphur

Answer : (b) Bromine.

[ Bromine is a non-metal that exists in a liquid state at room temperature. ]

35. Which of the following can undergo a chemical reaction?

(a)       (b)        (c)      (d)

Answer :  (d)

 [ In this case, iron (Fe) is displacing copper (Cu) from copper sulfate () in a single displacement reaction.]

36. Which one of the following figures correctly describes the process of electrolytic refining ?

Answer : (b) is correct .

[ In electrolytic refining , the anode consists of impure copper, the cathode consists of pure copper and impurities settle directly below the anode. ]

Short Answer Questions

37. Iqbal treated a 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.

Answer : The gas produced is Hydrogen. It can be identified by bringing a burning splint near the gas. Hydrogen burns with a ‘pop’ sound. The divalent lustrous metal M is Zinc.

Chemical equations are :

Reaction with sodium hydroxide: 

Reaction with hydrochloric acid: 

38. During extraction of metals, electolytic 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?

Answer :  (a) In electrolytic refining of Silver:

(i) Anode: Impure silver

(ii) Cathode: Thin sheet of pure silver

(b) Electrolyte: Silver nitrate solution ()

(c) Pure silver is deposited on the cathode (pure silver strip) after passing electric current through the electrolytic cell. The impurities from the silver anode move into the electrolyte or settle as anode mud.

39. Why should the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them?

Answer: Metal sulphides and carbonates are converted to metal oxides because it is easier to reduce a metal oxide to the free metal than to directly reduce a sulphide or carbonate.

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

Answer: When metals react with mineral acids, they generally form metal salts and liberate hydrogen gas. However, when metals (except Mn and Mg) react with nitric acid (  ), hydrogen gas is not evolved. This is because nitric acid is a strong oxidizing agent and oxidizes hydrogen to water and itself gets reduced to nitrogen oxides, preventing the liberation of hydrogen gas.

41. Compound X and aluminium are used to join railway tracks. (a) Identify the compound X (b) Name the reaction (c) Write down its reaction.

Answer: (a) The compound X is iron(III) oxide () .

 (b) The reaction is called the thermit reaction.

(c) The chemical reaction is:

  

42. When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

Answer : The metal X that reacts with cold water to give a basic salt Y and liberates a gas Z that easily catches fire is sodium.

X → Na  ,   Y → NaOH (sodium hydroxide)  and Z →  (hydrogen gas)

The reaction involved is:

43. A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

Answer: The non-metal X that exists in two different forms Y and Z is carbon.

X → Carbon (C)

Y→ Diamond (hardest natural substance)

Z→ Graphite (good conductor of electricity)

44. The following reaction takes place when aluminium powder is heated with .

     

(a) Is aluminium getting reduced? (b) Is  getting oxidised?

Answer: (a)  No, aluminium is getting oxidised.

 (b) No, MnO2​ is getting reduced .

45. What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?

Answer: Solder is an alloy made of lead (Pb) and tin (Sn).

The property that makes solder suitable for joining (welding) electrical wires is its low melting point. Because of this, solder melts easily and joins the wires without damaging them. It also provides a good electrical connection.

46. A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH.

Answer: The metal A used in the thermite process is typically aluminum (Al).

      

The oxide B formed is aluminum oxide (), which is amphoteric.

(a) Reaction of  with HCl :

    

 (b) Reaction with NaOH :

         

47. A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.

Answer : The metal that exists as a liquid at room temperature and is obtained by heating its sulphide in the presence of air is mercury (Hg).

Metal: Mercury (Hg)

Ore: Cinnabar (HgS)

The chemical reaction:

48. Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements.

(a) Mg and         (b) Li and           (c) Al and        (d) K and

Answer : (a) Mg and  : Magnesium nitride

Formula:

(b) Li and  : Lithium oxide

Formula: 

(c) Al and : Aluminum chloride

Formula:  ​

(d) K and  : Potassium oxide

Formula: 

49. What happens when

(a)  is heated in the absence of oxygen?

(b) a mixture  and  is heated?

Answer: (a)  is heated in the absence of oxygen:

Zinc carbonate (​) decomposes to form zinc oxide (ZnO) and carbon dioxide (​).

The chemical reaction: 

(b) Mixture of  and  is heated:

The mixture of copper(I) oxide () and copper(I) sulphide () reacts to form copper (Cu) and sulphur dioxide (​). 
The chemical reaction:

50. A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming

(a) Identify A, B and C

(b) To which Group of Periodic Table does A belong?

Answer:   (a) Non-metal A: Carbon (C)

Oxide B: Carbon monoxide (CO) - toxic

Oxide C: Carbon dioxide (  ) - contributes to global warming

(b) Group of Periodic Table for A (Carbon):

Carbon belongs to Group 14 of the Periodic Table.

51. Give two examples each of the metals that are good conductors and poor conductors of heat respectively.

Answer: Good Conductors of Heat:

(i) Copper (Cu): Copper is an excellent conductor of heat and is widely used in electrical and thermal applications.

(ii) Aluminum (Al): Aluminum is another metal known for its good thermal conductivity and is used in various heat transfer applications.

Poor Conductors of Heat (Insulators):

(i) Lead (Pb): Lead is a poor conductor of heat and is often used as a thermal insulator.

(ii) Mercury (Hg): Despite being a liquid at room temperature, mercury has relatively low thermal conductivity, making it a poor conductor of heat.

52. Name one metal and one non-metal that exist in liquid state at room temperature. Also name two metals having melting point less than 310 K (37°C)

Answer:  Metal in Liquid State at Room Temperature:

Mercury (Hg): Mercury is the only metal that is liquid at room temperature.

Non-metal in Liquid State at Room Temperature:

Bromine (): Bromine is a non-metal that exists in a liquid state at room temperature.

Metals with Melting Points Less than 310 K (37°C):

Gallium (Ga): Gallium has a melting point of approximately 303 K (-19°C).

Cesium (Cs): Cesium has a melting point of approximately 301 K (28°C).

53. An element A reacts with water to form a compound B which is used in white washing. The compound B on heating forms an oxide C which on treatment with water gives back B. Identify A, B and C and give the reactions involved.

Answer:  The element A : Calcium (Ca) .

Compound B : Calcium Hydroxide ( )-  used in white washing.

Oxide C : Calcium Oxide (CaO) .

Formation of B :  

Formation of C :  

Treatment of C with Water to Regenerate B :

Calcium (A) reacts with water to form calcium hydroxide (B), which on heating forms calcium oxide (C). Calcium oxide, when treated with water, regenerates calcium hydroxide.

54. An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

Answer : Alkali Metal A : Sodium (Na)

Compound B : Sodium hydroxide (NaOH) - formed when sodium reacts with water.

Compound C :  Sodium aluminate () - soluble in water.

The chemical reaction: 

         

55. Give the reaction involved during extraction of zinc from its ore by

(a) roasting of zinc ore        (b) calcination of zinc ore

Answer : (a) Roasting of Zinc Ore :

        

During the roasting process, zinc sulfide (ZnS) is heated in the presence of oxygen to form zinc oxide (ZnO) and sulfur dioxide ().

(b) Calcination of Zinc Ore:

During calcination, zinc carbonate () is heated to produce zinc oxide (ZnO) and carbon dioxide ().

56. A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.

Answer: Metal M : Copper (Cu)

 Black Coloured Product : Copper(II) oxide (CuO)

Reaction of Copper (M) with Oxygen :

Copper reacts with oxygen in the air to form copper(II) oxide. The black color of CuO gives a characteristic appearance to oxidized copper surfaces. However, copper does not liberate hydrogen from acids, indicating its lack of reactivity with acids.

57. An element forms an oxide  which is acidic in nature. Identify A as a metal or non-metal.

Answer: The oxide is acidic in nature. Generally, non-metals form acidic oxides, while metals form basic oxides. Therefore, A is a non-metal.

58. A solution of  was kept in an iron pot. After few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

Answer:  Iron is more reactive than copper. Therefore, iron displaces copper from copper sulphate solution.

When  solution was kept in an iron pot, iron slowly reacted with copper sulphate and got dissolved, forming iron sulphate. Due to this continuous reaction, holes were formed in the iron pot.

The reaction involved is:

Long Answer Questions

59. A non-metal A which is the largest constituent of air, when heated with in 1:3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.

(a) Identify A, B, C and D

(b) To which group of periodic table does this non-metal belong?

Answer: (a) Non-metal A: Nitrogen (

Gas B: Ammonia (

Oxide C: Nitrogen dioxide (

Acid D: Nitric acid (

(b) Group of Periodic Table for A (Nitrogen):

Nitrogen belongs to Group 15 of the Periodic Table.

Formation of Ammonia (B) : 

Formation of Nitrogen Dioxide (C):

Formation of Nitric Acid (D):

60. Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

Answer:  (i) Extraction of Metals from Sulphide Ores :

Concentration of ore → Metals of low reactivity →Sulphide ore →Roasting →Metal →Refining.

Roasting: The sulphide ore is heated in the presence of air to convert it into oxide.

   

Reduction/ heating: The oxide is then heated to obtain the metal.

    

Example: Extraction of mercury from cinnabar (HgS).

(ii) Metals of Medium Reactivity :

Concentration of ore → Metals of medium reactivity →Sulphide ore →Roasting →Oxide of metal →Reduction to metal→ Purification of metal.

Metals like zinc, iron and lead are extracted in the following steps:

(a) Concentration of Ore

Impurities are removed from the ore.

(b) Roasting : Sulphide ore is heated strongly in air to convert it into metal oxide.

Example:  

(c) Reduction of Metal Oxide

The metal oxide is reduced using carbon or carbon monoxide to obtain the metal.

     

Thus, sulphide ores are first converted into oxides by roasting, and then the oxides are reduced to obtain the metal.             

61. Explain the following

(a) Reactivity of Al decreases if it is dipped in  .

(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.

Answer: (a) Reactivity of Al decreases if it is dipped in

Nitric acid is a strong oxidising agent. It forms a thin protective layer of aluminium oxide (​) on the surface of aluminium. This layer prevents further reaction, so the reactivity of aluminium decreases.

(b) Carbon cannot reduce the oxides of Na or Mg

Sodium and magnesium are more reactive than carbon. Their oxides are very stable, so carbon cannot remove oxygen from them.

(c) NaCl is not a conductor of electricity in solid state whereas it conducts electricity in aqueous solution and molten state

In solid NaCl, ions are fixed in their positions and cannot move freely, so electricity is not conducted.

In molten state or aqueous solution, the ions become free to move and carry electric current, therefore NaCl conducts electricity.

(d) Iron articles are galvanised

Iron articles are galvanised by coating them with zinc to prevent rusting and corrosion. Zinc protects iron from air and moisture.

(e) Metals like Na, K, Ca and Mg are never found in free state in nature

These metals are highly reactive. They readily combine with oxygen, water and other substances present in nature to form compounds. Hence, they are not found in free state

62. (i) Given below are the steps for extraction of copper from its ore. Write the reaction involved.

(a) Roasting of copper (I) sulphide

(b) Reduction of copper (I) oxide with copper (I) sulphide.

(c) Electrolytic refining

(ii) Draw a neat and well labelled diagram for electrolytic refining of copper

Answer:  (a) Roasting of copper(I) sulphide:

      

(b) Reduction of copper(I) oxide with copper(I) sulphide:

      

(c) Electrolytic Refining:

In the electrolytic refining process, impure copper from the smelter is electrolysed. The anode is made of impure copper, and the cathode is made of pure copper. The electrolyte is a solution of copper sulphate ().

At the anode:

At the cathode:

(ii) Diagram for Electrolytic Refining of Copper:

 

In the diagram, the impure copper is the anode and pure copper is deposited at the cathode during the electrolytic refining process. The electrolyte is a solution of copper sulphate.

63. Of the three metals X, Y and Z. X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.

Answer: Metal X reacts with cold water:

Metal X is sodium (Na)

 The chemical reaction is: 

Metal Y reacts with hot water:

Metal Y is Magnesium (Mg)

 The chemical reaction is: 

Metal Z reacts with steam :

Metal Z is iron (Fe)

The chemical reaction is:

So, the order of increasing reactivity is: Iron (Z) < Magnesium (Y) < Sodium (X).

64. An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.

Answer: Element A burns with a golden flame in air. Element A reacts with another element B, which has an atomic number of 17, to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen.

A. Element A that burns with a golden flame is likely sodium (Na). Sodium burns with a characteristic golden-yellow flame.

B. The element with atomic number 17 is chlorine (Cl).

C. The product formed by the reaction of A and B is sodium chloride (NaCl).

D. The compound obtained by electrolysis of the aqueous solution of NaCl is sodium hydroxide (NaOH), and hydrogen gas () is liberated.

Now, let's write down the balanced chemical equations for the reactions:

The reaction between A (sodium) and B (chlorine): 

Electrolysis of aqueous sodium chloride solution:

65. Two ores A and B were taken. On heating ore A gives  whereas, ore B gives. What steps will you take to convert them into metals?

Answer: The ore A produces carbon dioxide ( upon heating, indicating that it might contain a carbonate ore, and ore B produces sulphur dioxide ( suggesting it could be a sulphide ore.

For Ore A (Carbonate Ore):

Heating to Produce Metal Oxide:  The carbonate ore (A) can be heated to produce the metal oxide and carbon dioxide.

For example, if A is a copper carbonate ore ( ), the reaction is:

Reduction of metal oxide: The chamical reaction:

For Ore B (Sulphide Ore):

Roasting to Produce Metal Oxide: The sulphide ore (B) can be roasted (heated strongly in the presence of air) to convert it into metal oxide and sulphur dioxide.

For example, if B is a copper sulfide ore ( ), the reaction is:

Reduction of Metal Oxide: The chamical reaction: