My Learn Edu

3. Metals and Non-metals

Class 10 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

(d) Ductility

Answer : (c) Dullness

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

(a) ductility

(b) malleability

(d) conductivity

Answer : (a) ductility

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)

Answer : (a) (i) and (ii)

Good thermal conductivity and good electrical conductivity.

[ (i) Good Thermal Conductivity: Aluminium's high thermal conductivity allows for efficient heat transfer, ensuring that the cooking utensil heats up quickly and distributes heat evenly. This property is crucial for cooking various dishes.

(ii) Good Electrical Conductivity: While electrical conductivity is not the primary reason for using aluminium in cooking utensils, it can be relevant for certain applications, such as electric stovetops or pans used in induction cooking. The electrical conductivity of aluminium makes it suitable for these purposes ]

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

(a) Na

(b) Ca

(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)

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

(d) Dil.HCl : Dil.

3 : 1

Answer : (c) Conc.HCl : Conc.

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)

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

(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)

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

[ Gold , silver , platinum … etc are found in the free state . ]

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)

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

(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

(d) Cu and Au

Answer : (a) Ni and Cr

[ In stainless steel, iron is mixed with (a) Ni (Nickel) and Cr (Chromium). ]

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

(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)

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

(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

(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

(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

(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)

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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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)

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 : Iqbal treated a lustrous, divalent element M with sodium hydroxide and hydrochloric acid, and observed the formation of bubbles in both reactions. This suggests that M is likely a metal that reacts with both acids and bases to produce hydrogen gas ().

To identify the produced gas as hydrogen, Iqbal can perform a simple test:

(i) Collect the gas in a test tube.

(ii) Bring a burning splint near the mouth of the test tube.

(iii) If the gas is hydrogen, it will produce a characteristic "pop" sound upon ignition.

The chemical reactions for both conditions are :

Reaction with sodium hydroxide (NaOH):

When a divalent metal M reacts with sodium hydroxide, it produces hydrogen gas and a metal hydroxide.

The general equation is:

For example, if M is zinc (Zn), the reaction would be:

Reaction with hydrochloric acid (HCl):

When a divalent metal M reacts with hydrochloric acid, it produces hydrogen gas and a metal chloride. The general equation is:

For example, if M is zinc (Zn), the reaction would be:

By performing the burning splint test and observing the characteristic "pop" sound, Iqbal can confirm that the gas produced in both reactions is hydrogen.

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) Anode and Cathode for Refining of Silver:

Anode: The impure silver metal is used as the anode.

Cathode: A thin strip of pure silver is used as the cathode.

(b) Suitable Electrolyte:

The suitable electrolyte for the refining of silver is silver nitrate ( ) solution.

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 during extraction because oxides are more easily reduced to pure metal. This conversion simplifies the extraction process by making the reduction step more efficient and effective, typically through methods like roasting and calcination.

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.

In this exothermic reaction, aluminium reduces iron(III) oxide to produce molten iron, which is used to weld railway tracks.

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)

Z = (hydrogen gas)

The reaction involved is:

In this reaction, sodium reacts with water to form sodium hydroxide and liberate hydrogen gas. The hydrogen gas produced can catch fire due to its flammable nature.Top of Form

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)

In diamond (Y), carbon atoms are tetrahedrally bonded, forming a three-dimensional network, making it hard. In graphite (Z), carbon atoms are arranged in layers with weak forces between the layers, allowing for the conductivity 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, is getting reduced .

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

Answer : Solder alloys are consist of tin (Sn) and lead (Pb).

Its low melting point makes it suitable for welding electrical wires, as it can create strong electrical connections without damaging the components due to excessive heat.

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 :

In these reactions, aluminum oxide shows amphoteric behavior by reacting with both acidic (HCl) and basic (NaOH) substances.

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 reaction :

In this reaction, cinnabar (mercury sulphide) is heated in the presence of air to produce liquid mercury and sulfur dioxide.

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

(d) K and

Answer : (a) Mg and : Magnesium nitride

Formula:

(b) Li and : Lithium oxide

Formula:

(d) K and : Potassium oxide

Formula:

49. What happens when

(a) is heated in the absence of oxygen?

(b) a mixture of and is heated?

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

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

(b) Mixture of and is heated:

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

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:

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

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):

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

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 : 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.

Reaction:

In the given reactions, sodium reacts with water to form sodium hydroxide, and when sodium hydroxide reacts with aluminum oxide, it forms sodium aluminate.

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 (ZnCO3) 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 that is acidic in nature suggests that element A is a non-metal. Non-metals tend to form acidic oxides, whereas metals generally form basic or amphoteric oxides.

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 : The reaction is due to the higher reactivity of iron compared to copper. In the presence of copper sulphate (), iron undergoes displacement and corrodes. The reaction can be represented as:

Iron (Fe) displaces copper (Cu) from copper sulfate, forming ferrous sulphate () and depositing copper. The released copper can accumulate on the iron surface, leading to the formation of holes due to the continuous corrosion process.

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 (N₂)

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.

Chemical Reactions:

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 : The extraction of metals of low reactivity from their respective sulphide ores typically involves the following steps:

Extraction of Metals of Low Reactivity (e.g., Copper):

Roasting: The concentrated ore is roasted in the presence of excess air to convert the sulphide ore into oxide.

The extraction of metals of medium reactivity from their respective sulphide ores typically involves the following steps:

Extraction of Metals of Medium Reactivity (e.g., Zinc):

Concentration of Ore: The sulphide ore is concentrated by froth flotation.

Roasting: The concentrated ore is roasted in the presence of excess air to convert the sulphide ore into oxide.

Reduction: The oxide is then reduced to the metal by heating with carbon or coke.

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 :

Aluminum forms a protective oxide layer ( ) on its surface when exposed to air. Nitric acid () is a strong oxidising agent that can dissolve this protective oxide layer, exposing fresh aluminum. However, this makes aluminum less reactive over time as the protective layer diminishes.

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

Sodium (Na) and magnesium (Mg) are more reactive than carbon. Carbon is unable to displace these metals from their oxides because sodium and magnesium have a higher reactivity, and the carbon reduction process is not feasible.

In the solid state, the ions in NaCl are fixed in a rigid structure and cannot move to conduct electricity. In the molten state and aqueous solution, the ions are free to move, allowing the solution or molten salt to conduct electricity.

(d) Galvanization of Iron Articles:

Galvanization involves coating iron or steel with a layer of zinc to protect it from corrosion. Zinc acts as a sacrificial anode and corrodes preferentially, preventing the underlying iron or steel from rusting.

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

These metals are highly reactive and readily form compounds with other elements. They are found in nature as compounds such as oxides, carbonates, or chlorides rather than in their free metallic state due to their high reactivity with oxygen and other elements.

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.

(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:

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 sulfate.

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 reaction :

Metal Y reacts with hot water:

Metal Y is Magnesium (Mg)

The reaction :

Metal Z reacts with steam :

Metal Z is iron (Fe)

The reaction :

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.

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. To extract metals from these ores, different processes are typically employed.

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 would be:

Reduction of Metal Oxide:

Using carbon (in the form of coke) as a reducing agent is common:

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 would be:

Reduction of Metal Oxide:

Using carbon (in the form of coke) as a reducing agent is common:

These are general steps, and the specific details may vary depending on the type of ore and the metal you are trying to extract. Always refer to the specific chemical reactions for the particular metal and ore you are working with.