NCERT Exemplar Solutions Class 10 Science Metals and Non Metals

Read NCERT Exemplar Solutions Class 10 Science Metals And Non-Metals below, students should study NCERT Exemplar class 10 Science available on Studiestoday.com with solved questions and answers. These chapter wise answers for class 10 Science Exemplar problems have been prepared by teacher of Grade 10. These NCERT Exemplar class 10 Science solutions have been designed as per the latest NCERT syllabus for class 10 and if practiced thoroughly can help you to score good marks in standard 10 Science class tests and examinations


Multiple Choice Questions...............................


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

(a) Electrical conduction

(b) Sonorous in nature

(c) Dullness

(d) Ductility 

Solution 1: (c) Dullness

Dullness is not shown by metals.

 

Question 2:  The ability of metals to be drawn into thin wires is known as

(a) ductility

(b) malleability

(c) sonorousity

(d) conductivity 

Solution 2: (a) ductility

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

 

Question 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) 

Solution 3:  (d) (i) and (iv)

Since ductility and electric conductivity have no effect on cooking, the correct answers are thermal conductivity and a high melting point.

 

Question 4:  Which one of the following metals does not react with cold as well as hot water?

(a) Na

(b) Ca

(c) Mg

(d) Fe 

Solution 4: (d) Fe

Magnesium reacts with hot water to form Magnesium Oxide, while sodium and calcium react vigorously with water. Iron is unaffected by cold or hot water, although it is affected by steam.

 

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

(a) FeO

(b) Fe2O3

(c) Fe3O4

(d) Fe2O3 and Fe3O4 

Solution 5:  (c) Fe3O4

3Fe + 4H2O → Fe3O4 + 4H2

 

Question 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) 

Solution 6: (d) (iii) and (iv)

Calcium forms hydrogen as it reacts strongly with water, allowing calcium to float.

 

Question 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) H2SO4

(b) HCl

(c) HNO3

(d) All of these 

Solution 7:  (c) HNO3

Nitric acid is an extremely strong oxidizer. It forms water as it reacts with the metal.

 

Question 8:  The composition of aqua-regia is

(a) Dil.HCl: Conc. HNO3 3: 1

(b) Conc.HCl: Dil. HNO3 3 : 1

(c) Conc.HCl: Conc. HNO3 3 : 1

(d) Dil.HCl: Dil. HNO3 3: 1 

Solution 8:   (c) Conc.HCl: Conc. HNO3 3: 1 

The composition of aqua-regia is Conc.HCl: Conc. HNO3 3: 1

 

Question 9:  Which of the following are not ionic compounds?

(i) KCl

(ii) HCl

(iii) CCl4

(iv) NaCl

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)

(d) (i) and (iii) 

Solution 9: (b) (ii) and (iii)

Since HCl and CCl4 are covalent compounds, they are unable to be ionic.

 

Question 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 a molten state 

Solution 10:  (b) Electrical conductivity in solid-state

Since free ions are not present in the solid state of an ionic compound, solid ionic compounds cannot conduct electricity.

 

Question 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) 

Solution 11:  (c) (ii) and (iv)

Gold and silver are non-reactive metals, which mean they remain in their natural state.

 

Question 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) 

Solution 12:  (d) (iii) and (iv)

Since sodium and potassium are at the top of the reactivity scale, they can be refined by electrolytic refining.

 

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

(a) Ag3N

(b) Ag2O

(c) Ag2 S

(d) Ag2S and Ag3N 

Solution 13:  (c) Ag2S

Ag2S is formed when silver metal reacts with sulphur in the atmosphere. The black coloration of silver articles is caused by Ag2S.

 

Question 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 

Solution 14:  (c) Zinc

Galvanization is the electrolysis-based application of a zinc layer to iron.

 

Question 15:  Stainless steel is a 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 

Solution 15:  (a) Ni and Cr 

Stainless steel is iron, nickel and chromium alloy. This alloy gives the metal its strength, durability, and resistance to corrosion.

 

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

(a) CuSO4

(b) CuCO3

(c) Cu(NO3)2

(d) CuO 

Solution 16:  (d) CuO

Copper reacts with ambient oxygen to create a green copper oxide layer when exposed to air.

 

Question 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 

Solution 17:  (d) Hg

Generally, metals are solid in nature but mercury (Hg) is found in liquid state at room temperature.

 

Question 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) 

Solution 18:  (d) (i) and (ii) 

In the reactivity sequence, sodium and calcium are at the top.

 

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

(a) Sulphur

(b) Oxygen

(c) Nitrogen

(d) Iodine 

Solution 19:  (d) Iodine

Generally, non-metals are not lustrous but iodine one of the no n-metal which is lustrous.

 

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

(a) Mg

(b) Ag

(c) Zn

(d) Cu 

Solution 20: (b) Ag

Silver is a non-reactive metal that can be readily displaced.

 

Question 21:  2 mL each of concentrated HCl, HNO3 and a mixture of concentrated HCl and concentrated HNO3 in the ratio of 3: 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each 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 

Solution 21:  (b) Au

Since solution C is a mixture of concentrated HCL and concentrated HNO3 known as aqua regia, the response is gold. Gold dissolves in Aqua Regia.

 

Question 22:  An alloy is

(a) an element

(b) a compound

(c) a homogeneous mixture

(d) a heterogeneous mixture 

Solution 22: (c) a homogeneous mixture

Since its composition is uniform, an alloy is a homogeneous mixture.

 

Question 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) 

Solution 23:  (b) (iii) and (iv)

An electrolytic cell consists of positively charged anode and negatively charged cathode.

 

Question 24: During electrolytic refining of zinc, it gets

(a) deposited on cathode

(b) deposited on anode

(c) deposited on the cathode as well as anode

(d) remains in the solution 

Solution 24:  (a) deposited on cathode 

Zinc is positively charged, so it gravitates toward the cathode, which is negatively charged.

 

Question 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 the air. It reacts vigorously with water. Identify the element from the following

(a) Mg

(b) Na

(c) P

(d) Ca 

Solution 25:  (b) Na

Sodium is a soft material that can be quickly sliced with a knife. Since sodium reacts violently with water and air, it is kept in kerosene.

 

Question 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 

Solution 26: (d) Steel

Steel is a carbon-iron alloy with carbon as a non-metal component.

 

Question 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 

Solution 27:  (b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas

Magnesium reacts with cold water to form magnesium oxide, which then emits hydrogen gas, which is incorrect since Magnesium Hydroxide, not Magnesium Oxide, is formed.

 

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

(a) Stainless steel

(b) Alnico

(c) Solder

(d) Zinc amalgam 

Solution 28: (d) Zinc amalgam

Mercury and Zinc makes a combination named as Zinc amalgam.

 

Question 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 a high melting point

(b) Has a low melting point

(c) Conducts electricity in molten state

(d) Occurs as solid 

Solution 29: (b) Has a low melting point

Option b) is incorrect since Z is an ionic compound, and ionic compounds have melting points.

 

Question 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 

Solution 30:  (d) Y is a non-metal and Z is a metal

Element Y has three electrons in its outer shell, making it electronegative. Z is electropositive since it has two electrons in its outermost shell. As a consequence, it is a metal.

 

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

(a) Na

(b) Ca

(c) Al

(d) Cu 

Solution 31: (c) Al

Aluminium oxides are acidic and basic in nature. As a result, aluminium oxides are amphoteric metal oxide.

 

Question 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  

Solution 32:  (b) Graphite

Generally, non-metals are not conductors of electricity but graphite is a good conductor of electricity.

 

Question 33:  Electrical wires have a coating of an insulating material. The material, generally used is

(a) Sulphur

(b) Graphite

(c) PVC

(d) All can be used 

Solution 33: (c) PVC 

Since sulphur is brittle in nature, it can be used as an insulator, whereas graphite is a strong conductor of electricity and thus cannot be used as an insulator.

 

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

(a) Carbon

(b) Bromine

(c) Phosphorus

(d) Sulphur 

Solution 34:  (b) Bromine 

Bromine is the non-metal which is liquid in state.

 

Question 35:  Which of the following can undergo a chemical reaction?

(a) MgSO4 + Fe

(b) ZnSO4 + Fe

(c) MgSO4 + Pb

(d) CuSO4 + Fe 

Solution 35:  (d) CuSO4 + Fe

Since iron is more reactive than copper, it displaces copper to form FeSO4.

 

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

NCERT Exemplar Solutions Class 10 Science Metals And Non-Metals


Solution 36:  (b)  Copper ions are scattered and deposited on the negatively charged cathode from the positively charged anode.

 

Short Answer Questions.............................


Question 37:  Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in a reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how he can identify the produced gas. Write chemical equations for both the reactions. 

Solution 37:   A lighted matchstick should be brought close to the gas to mark it. The evolution of Hydrogen gas is shown when a matchstick burns with a "pop" tone.

M + 2NaOH → Na2MO2 + H2 

With hydrochloric acid in place of sodium hydroxide:

M + 2HCl → MCl2 + H2

 

Question 38:  During the 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? 

Solution 38:

  1. For electrolytic processing of silver metal, impure metal will be used as an anode and pure metal will be used as a cathode during metal extraction.
  2. A suitable electrolyte is Silver Sulphate or Silver Nitrate.
  3. On the cathode, pure silver is collected. 

 

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

Solution 39:  Metal sulphides and carbonates are converted to metal oxides during the extraction process because metals are easier to acquire in oxide form than they are in sulphide or carbonate form.

 

Question 40:  Generally, when metals are treated with mineral acids, hydrogen gas is liberated, but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why? 

Solution 40:   HNO3 is an extremely strong oxidizer. When converting itself to nitrogen oxide, it oxidises the liberated Hydrogen into the water.

 

Question 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. 

Solution 41: 

  1. Compound X is Fe2O3.
  2. The reaction in question is a thermite reaction, also known as aluminothermy.
  3. Heat Ferric oxide Aluminium Iron Oxide Fe2O3(s) + 2Al(s) →  Al2O3(s) + 2Fe(s)

 

Question 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. 

Solution 42:   Since NaOH has a molecular mass of 40, X is Na.

As a result, Y is NaOH.

Z is a hydrogen gas that ignites when it comes into contact with water.

2Na + 2H2O  →  2NaOH + H2

 

Question 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. 

Solution 43:  Carbon is X, Y, and Z, and Diamond and Graphite are allotropes of carbon.

 

Question 44:  The following reaction takes place when the aluminium powder is heated with MnO2

3 MnO2 (s) + 4 Al (s) → 3 Mn (l) + 2 Al2O3 (l) + Heat

(a) Is aluminium getting reduced? (b) Is MnO2 getting oxidised? 

Solution 44:  Aluminum is oxidised in this reaction when oxygen is mixed with it. MnO2 is being depleted when oxygen is removed from it.

 

Question 45:  What are the constituent of solder alloy? Which property of solder makes it suitable for welding electrical wires? 

Solution 45:   Lead and aluminium are used to make solder alloy. It can be used to solder electrical wires due to its low melting point.

 

Question 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. 

Solution 46:   Metal A is Aluminium and oxide B is Al2O3. 

Reaction with HCl:

Al2O3 + 6HCl → 2AlCl3 + 3H2

Reaction with NaOH:

Al2O3 + 2NaOH  → 2NaAlO2 + H2O

 

Question 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. 

Solution 47:   Mercury is a liquid metal that can be found at room temperature. Cinnabar is a Mercury ore. The following reaction occurs when we heat cinnabar in atmospheric oxygen.

2HgS + 3O2→  2HgO + 2SO2 

Mercury and oxygen are obtained by heating mercuric oxide once more.

2HgO → heat Hg + O2

 

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

(a) Mg and N2

(b) Li and O2

(c) Al and Cl2

(d) K and O2 

Solution 48:

(a) Magnesium Nitride (Mg3N2)

(b) Lithium Oxide ( Li2O)

(c) Aluminium Chloride ( AlCl3)

(d) Potassium Oxide ( K2O)

 

Question 49:  What happens when

(a) ZnCO3 is heated in the absence of oxygen?

(b) a mixture of Cu2O and Cu2S is heated? 

Solution 49:  a) Zinc Oxide and Carbon Dioxide are liberated as ZnCO3 is heated in the absence of oxygen.

ZnCo→ ZnO + CO2 

b) Pure copper is obtained by heating a mixture of Cu2O and Cu2S.

2 Cu2O + Cu2S → 6Cu + SO2

 

Question 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? 

Solution 50:

a) Carbon is the letter A, Carbon monoxide is B, and carbon dioxide is C.

b) Carbon belongs to Group 14 of Periodic Table.

 

Question 51:  Give two examples each: The metals that are good conductors and poor conductors of heat, respectively. 

Solution 51:   Good conductors of heat are Iron and Copper. Bad conductors of heat are Lead and Mercury.

 

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

Solution 52:   At room temperature, mercury and bromine are also liquids. Metals with melting points less than 310K (37°C) include caesium and gallium.

 

Question 53:  An element A reacts with water to form a compound B which is used in whitewashing. 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. 

Solution 53:  Calcium is A, Calcium Hydroxide is B, and Calcium Oxide is C.

Calcium reacts with water and gives:

Ca + 2H2O → Ca(OH)2 + H2

 

Calcium hydroxide on heating gives:

Ca(OH)→ CaO + H2O

 

Calcium oxide on treating with water gives:

CaO + H2O → Ca(OH)2

 

Question 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. 

Solution 54:    The letters A and B stand for sodium and sodium hydroxide, respectively. Since NaOH has a molecular mass of 40. As a consequence, C stands for Sodium Aluminate.

Al2O3 + 2NaOH → 2NaAlO2 + H2O

 

Question 55:   Give the reaction involved during the extraction of zinc from its ore by (a) roasting of zinc ore (b) calcination of zinc ore. 

Solution 55:

(a) Roasting of zinc ore

2ZnS + 3O2 → 2ZnO + 2SO2 

(b) Calcinations of zinc ore

ZnCo3 → ZnO + CO

 

Question 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. 

Solution 56:   Copper is the only metal that is untouched by acids. Copper Oxide is formed when it reacts with oxygen. Copper is the metal M, and copper oxide is the black-coloured product.

2Cu  + O2  → 2CuO

 

Question 57:  An element forms an oxide A2O3 which is acidic in nature. Identify A as metal or non-metal. 

Solution 57:   Since non-metal oxides are acidic in nature, A is a non-metal.

 

Question 58:  A solution of CuSO4 was kept in an iron pot. After a 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. 

Solution 58:   Since iron is more reactive than copper, it displaces copper, resulting in FeSO4. A portion of the iron is dissolved during this process, resulting in holes in the pot.

Fe + CuSO→ FeSO+ Cu


Long Answer Questions..........................


Question 59:  A non-metal A which is the largest constituent of air, when heated with H2 in 1:3 ratio in the presence of a catalyst (Fe) gives a gas B. On heating with O2 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? 

Solution 59:   a) Nitrogen is the non-metal "A" since it is the most abundant part of air, accounting for about 78 percent of all gases. The letters B, C, and D stand for ammonia, nitrogen dioxide, and nitric acid, respectively.

The following reaction occurs when H2 is heated in a 1:3 ratio in the presence of a catalyst (Fe).

3N2+ 3H→ 2NH3 

Nitrogen-dioxide is formed when nitrogen is heated with oxygen.

N+ 3O → 2NO2 

When nitrogen dioxide is dissolved in water in the presence of oxygen, nitric acid is produced.

NO2 + H2O → HNO3 

b) Nitrogen belongs to group 15 of Periodic Table.

 

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

Solution 60:   As low and medium reactivity metals are extracted from their respective sulphide ores.

They are first heated in the presence of oxygen from the atmosphere. Metal oxides will be released during this process. This move is used because it is a faster way to remove methods.

Ex: Cinnabar is heated in the presence of air to cause mercuric sulphide to oxidise, yielding mercuric oxide.

2HgS + 3O→ 2HgO + 2SO2                

Mercuric oxide adds to the heat needed to obtain Mercury.

2HgO → 2Hg + O2

Zinc is a medium-reactive metal whose ore is Zinc Blend.

To obtain Zinc oxide, the Zinc Blend is roasted.

2ZnS + 3O2  → 2ZnO + 2SO2

ZNCO3 → ZnO + CO2

When zinc oxide is heated with CO2, zinc is formed.

ZnO + C→  Zn + CO

 

Question 61:  Explain the following:

(a) Reactivity of Al decreases if it is dipped in HNO3

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

(c) NaCl is not a conductor of electricity in the 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. 

Solution 61:  

a) Since HNO3 is a potent oxidising agent, it reduces the reactivity of aluminium when dipped in it. A film of aluminium oxide is deposited here, which reduces the reactivity of aluminium. 

(b) Since Na and Mg are highly reactive metals, carbon cannot reduce their oxides. Carbon has a lower affinity for Na and Mg than oxygen. As a result, carbon is unable to reduce the oxides of sodium and magnesium. 

(c) Since NaCl is an ionic compound, it does not conduct electricity in the solid state, but it does conduct electricity in aqueous solution and in the molten state. Ionic compounds can't conduct electricity in the solid state, but they can in aqueous solution and molten state. 

d) Rust is formed when iron reacts with oxygen in the air. It is galvanised to keep the iron from rusting. 

e) Highly reactive metals include Na, K, Ca, and Mg. They can combine nearly all elements to form compounds. As a result, they are seldom seen in nature in their natural state.

 

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

(a) Roasting of copper (1) sulphide

(b) Reduction of copper (1) oxide with copper (1) sulphide.

(c) Electrolytic refining

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

Solution 62:

(i) (a) 2Cu2S + 3O2 → 2Cu2O + SO2

(b) 2Cu2O + Cu2S → 6Cu + SO2

(c) Cu+2+ 2e→ Cu

 

NCERT Exemplar Solutions Class 10 Science Metals And Non-Metals

 

Question 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.

 Solution 63: 

Cold water responds with X.

As a result, sodium should be the ingredient.

Ca + H₂O → Ca(OH)₂ + H₂ 

Since Y reacts with hot water, it is called "Magnesium."

Mg + H₂O →  Mg(OH)₂ + H₂ 

Just steam responds with Z. As a result, it is Iron.

Fe + H₂O → Fe₂O₃+  H₂ 

Putting them in ascending order (increasing order of reactivity)

Fe < Mg < Ca

 

Question 64:  An element A burns with golden flame in the 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. 

Solution 64:   Since it burns with a golden flame in the air, Element A is 17 Sodium.

Chlorine, with an atomic number of 17, is element B.

Sodium Chloride is Substance C.

2Na + CL→ 2NaCl 

Sodium hydroxide is Substance D.

2NaCl + 2H2O → 2NaOH + Cl2+H2

 

Question 65:  Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2. What steps will you take to convert them into metals? 

Solution 65:

Ore A is a carbonate ore since it absorbs CO2 when heated.

Steps involved in Extraction of ore A are: 

a) Calcination

To make a metal oxide, ore is heated in a small amount of air.

ACO3 → AO + CO2 

b) Reduction

To obtain metal, the metal oxide is reduced with coke.

AO + C→ A + CO 

 

Ore B is a sulphide ore

Steps involved in the extraction of element B are: 

a) Roasting

To produce a metal oxide, ore is heated in the presence of air.

2BS + 3O2 → 2BO + 2SO2 

b) Reduction

Carbon reduces the metal oxide to metal.

BO + C → B + CO

Chapter 16 Sustainable Management of Natural Resources
NCERT Exemplar Solutions Class 10 Science Management of Natural Resources