NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

Science Class 10

Class 10 : NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

The document NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev is a part of the Class 10 Course Science Class 10.
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Short Answer Type Questions

Q.1. Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in the 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.
Ans.

  • M + 2NaOH → Na2MO+ H2(g)
  • M + 2HCl → MCl2 + H2(g)
  • Bring a burning candle near the gas. 
  • If it burns with a pop sound, the gas is hydrogen, and the element is a metal.


Q.2. 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?

Ans. (a) Pure silver rod will be used as cathode, and impure silver rod will be used as the anode.

NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

Electrolyte Refining

(b) AgNO3(aq) can be used as the electrolyte.
(c) Pure silver will be formed at the cathode.
At anode : Ag → Ag+ + e-
At cathode : Ag+ + e- → Ag

Q.3. Why should the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them?
Ans. It is because it is easier to reduce metal oxides to get free metals as compared to metal sulphides and metal carbonates.

Q.4. 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?
Ans. It is because HNO3 is an oxidising agent and it gets reduced to NO if it is dilute and NO2 if HNO3 is concentrated, it oxidises H2 to H2O.

Q.5. Compound X and aluminium are used to join railway tracks.
(a) Identify the compound X.
(b) Name the reaction.
(c) Write down its reaction.

Ans. (a) ‘X ’ is Fe2O3.
(b) It is called thermite reaction.

(c) NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
Molten iron is used to form broken railway tracks.

Q.6. 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.

Ans.

  • Both sodium (Na) and potassium (K) react with cold water to give basic salt NaOH and KOH respectively. Since the molecular mass of XOH is 40, therefore, the metal X is Na. Since, the molecular mass of NaOH is 40 (23 + 16 + 1 = 40). 
  • Therefore, Y is NaOH and the gas liberated during the reaction is hydrogen. Thus, Z is H2.
    2Na + 2H2O → 2NaOH + H2 + Heat energy


Q.7. The following reaction takes place when aluminium powder is heated with MnO2
NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
(a) Is aluminium getting reduced?
(b) Is MnO2 getting oxidised?

Ans. (a) No, aluminium is getting oxidised.
(b) No, MnO2 is getting reduced.

Q.8. What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?
Ans.

  • Solder is made up of lead and tin
  • It has low melting point, therefore, it is used for soldering (welding) electrical wires.


Q.9. 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.
Ans.

  • ‘A’ is aluminium.
    4Al(s) + 3O2NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev 2Al2O3(s)
  • 'B' is amphoteric in nature(Al2O3).
     Al2O3 + 6HCl → 2AlCl3 + 3H2O
     Al2O3 + 2NaOH → 2NaAlO2 + H2O

Q.10. A metal that exists as 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.
Ans. The metal is mercury.
 2HgS(s) + 3O2 → 2HgO + 3SO2(g)
 HgS(s) + 2HgO → 3Hgl(l) + SO2(g)

Q.11. Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements:
(a) Mg and N2
(b) Li and O2
(c) Al and Cl2
(d) K and O
2
Ans.
(a) 3Mg + Mg3N2 → Mg3N2
(b) 4Li + O2 → 2Li2O
(c) 2Al + 3Cl2 → 2AlCl3
(d) 4K + O2 → 2K2O

Q.12. What happens when
(a) ZnCO3 is heated in the absence of oxygen?
(b) a mixture of Cu2O and Cu2S is heated?
Ans.
(a) 

  • Zinc oxide(s) and CO2(g) are formed.
    ZnCO3NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRevZnO + CO2
  • Blister copper(s) and SO2(g) are formed.

(b) 2Cu2O + Cu2S(s)NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev6Cu(s) + SO2(g)

Q.13. A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas oxide C causes global warming,
(a) Identity A, B and C.
(b) To which group of periodic table does A belong?

Ans. (a) 

  • ‘A’ is carbon. 
  • It forms two oxides: 
    (i) CO (B) is toxic
    (ii) Whereas CO2 (C) causes global warming as it absorbs heat radiations from atmosphere.
    (b) ‘A’ belongs to group 14 of periodic table.

Q.14. 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.
Ans.
NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

Q.15. 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.
Ans. M is 'Cu' It does not liberate hydrogen with dilute acid as it is less reactive than hydrogen gas.
NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

Q.16. 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.
Ans.

  • Iron is more reactive than copper. 
  • Therefore, it displaces copper from copper sulphate solution.
    NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
  •  A portion of the iron pot got dissolved in this process and caused holes in it.

Long Answer Type Questions

Q.17. A non-metal A which is the largest constituent of air, when heated with H2 in 1 : 3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with 0 2, 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?
Ans. (a)

  • N2 is largest constituent of air when heated with H2 in the ratio of 1 : 3 in the presence of a catalyst (Fe) gives a gas NH3(B).
    NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
  • Nitrogen reacts with oxygen on heating to form nitrogen monoxide 'C' which gets oxidised in the presence of O2 to nitrogen dioxide. Nitrogen dioxide dissolves in water in the presence of oxygen to form nitric acid, which is an oxidising agent.
    NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
  • 'A' is N2, 'B' isNH3, 'C' is NO and 'D' is HN03.
    (b) Group 15

Q.18. Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
Ans.

NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

  • Metal sulphide like HgS reacts with O2 on heating to form mercuric oxide, HgO and sulphur dioxide, SO2.
    2HgS + 3O2 NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev 2HgO + 2SO2
  • Mercuric oxide on further heating gives Hg which can be refined by distillation.
    2HgONCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev2Hg + O2
  • In the same manner, copper in copper glance, Cu2S is found in nature and can be obtained from its ore by heating in air:
    2Cu2S + 3O2 NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev 2Cu2O + 2SO2
    2Cu2O + Cu2S → 6Cu + SO2
  • Pure copper is obtained from electrolytic refining.

(b)

NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev

  • Sulphide ore like zinc blende (ZnS) on roasting in the presence of O2 gives metal oxide. On reduction with suitable reducing agent gives metal which is impure.
  • Impure metal on electrolytic refining gives pure metal.
    NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
  • Pure zinc is obtained by electrolytic refining.

Q.19. Explain the following
(а) 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 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.

Ans. (a) It is due to the formation of oxide layer on its surface.
(b) It is because Na or Mg are strong reducing agents, therefore, carbon cannot reduce their oxides.
(c) NaCl does not conduct electricity in solid state as it does not have free ions to move in solid-state but in aqueous solution and in molten states ions are free to move.
(d) Iron articles are galvanised to protect them from rusting.
(e) It is because these metals are highly reactive and occur in the form of their compounds.

Q.20. 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.
Ans.

  • ‘A’ is sodium as it bums with golden flame in air.
  • ‘B ’ (17) has electronic configuration 2, 8, 7 so ‘B ’ is chlorine
    NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev
    ‘A’ is Na, ‘B’ is Cl2, ‘C’ is NaCl and ‘D’ is NaOH.

Q.21. 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 then into metals?
Ans.

  • Ore A gives CO2, therefore, it is a carbonate ore. Ore ‘A’ is first subjected to calcination, followed by reduction.
    MCO3NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRevMO + CO2
    MO + C NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev M + CO
  • Ore B gives SO2, therefore, it is a sulphide ore. Ore B is first subjected to roasting followed by reduction.
    2MS + 3O2 NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev 2MO + 2SO2
    MO + C NCERT Exemplar - Metals and Non-metals Class 10 Notes | EduRev M + CO
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