CBSE Class 12 Chemistry General Principles and Processes of Isolation of Elements MCQs Set B

Question. Which one is malachite from the following?
(a) CuCO₃.Cu(OH)₂
(b) CuFeS₂
(c) Cu(OH)₂
(d) Fe₃O₄

Answer : A

Question. Identify the incorrect statement.
(a) The scientific and technological process used for isolation of the metal from its ore is known as metallurgy.
(b) Minerals are naturally occurring chemical substances in the earth’s crust.
(c) Ores are minerals that may contain a metal.
(d) Gangue is an ore contaminated with undesired materials.

Answer : D

Question. Considering Ellingham diagram, which of the following metals can be used to reduce alumina?
(a) Fe
(b) Zn
(c) Mg
(d) Cu

Answer : C

Question. In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with
(a) carbon monoxide
(b) copper (I) sulphide
(c) sulphur dioxide
(d) iron (II) sulphide.

Answer : B

Question. Aluminium is extracted from alumina (Al₂O₃) by electrolysis of a molten mixture of
(a) Al₂O₃ + HF + NaAlF₄
(b) Al₂O₃ + CaF₂ + NaAlF₄
(c) Al₂O₃ + Na₃AlF₆ + CaF₂
(d) Al₂O₃ + KF + Na3AlF₆

Answer : C

Question. Purification of aluminium, by electrolytic refining, is known as
(a) Hoope’s process
(b) Baeyer’s process
(c) Hall’s process
(d) Serpeck’s process.

Answer : A

Question. The process does not involve a catalyst is :
(a) Haber process
(b) Contact process
(c) Thermite process
(d) Ostwald process

Answer : C

Question. Chief ore of Al is :
(a) cryolite
(b) bauxite
(c) feldspar
(d) kaolin

Answer : B

Question. Which of the following is a carbonate ore?
(a) Pyrolusite
(b) Malachite
(c) Diaspore
(d) Cassiterite

Answer : B

Question. Carbon and CO gas are used to reduce which of the following pairs of metal oxides for extraction of metals?
(a) FeO, SnO
(b) SnO, ZnO
(c) BaO, Na₂O₂
(d) FeO, ZnO

Answer : D

Question. The main reactions occurring in blast furnace during extraction of iron from haematite are________.
(i) Fe₂O₃ + 3CO → 2Fe + 3CO₂
(ii) FeO + SiO₂ → FeSiO₃
(iii) Fe₂O₃ + 3C → 2Fe + 3CO
(iv) CaO + SiO₂ → CaSiO₃
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (i) and (iv)
(d) (i), (ii) and (iii)

Answer : C

Question. 2CuFeS₂ +O₂ →Cu₂S + 2FeS + SO₂ Which process of metallurgy of copper is represented by above equation?
(a) Concentration
(b) Roasting
(c) Reduction
(d) Purification

Answer : B

Question. “Metals are usually not found as nitrates in their ores.” Out of the following two (I and II) reasons which is/are true for the above observation?
I. Metal nitrates are highly unstable.
II. Metal nitrates are highly soluble in water.
(a) I is false but II is true.
(b) I is true but II is false.
(c) I and II are true.
(d) I and II are false

Answer : A

Question. Which one of the following is a mineral of iron?
(a) Malachite
(b) Cassiterite
(c) Pyrolusite
(d) Magnetite

Answer : D

Question. Cassiterite is an ore of
(a) Sb
(b) Ni
(c) Mn
(d) Sn

Answer : D

Question. The following reactions take place in the blast furnace in the preparation of impure iron. Identify the reaction pertaining to the formation of the slag.
(a) Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
(b) CaCO₃(s) → CaO(s) + CO₂(g)
(c) CaO(s) + SiO₂(s) → CaSiO₃(s)
(d) 2C(s) + O₂(g) → 2CO(g)

Answer : C

Question. Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
(a) The DGf° of the sulphide is greater than those for CS₂ and H₂S.
(b) The DGf° is negative for roasting of sulphide ore to oxide.
(c) Roasting of the sulphide to the oxide is thermodynamically feasible.
(d) Carbon and hydrogen are suitable reducing agents for metal sulphides.

Answer : D

Question. Nitriding is the process of surface hardening of steel by treating it in an atmosphere of
(a) NH₃
(b) O₃
(c) N₂
(d) H₂S

Answer : A

Question. Flux is used to remove :
(a) basic impurities
(b) acidic impurities
(c) all types of impurities
(d) acidic and basic both impurities

Answer : D

Question. Mac Arthur process is used for the extraction of:
(a) Au
(b) Pt
(c) Cu
(d) Zn

Answer : A

Question. In the extraction of copper from its sulphide ore, the metal is formed by reduction of Cu₂O with :
(a) FeS
(b) CO
(c) Cu₂S
(d) SO₂

Answer : C

Question. Sulphide ores of metals are usually concentrated by froth floatation process. Which one of the following sulphide ores offer an exception and is concentrated by chemical leaching?
(a) Galena
(b) Copper pyrite
(c) Sphalerite
(d) Argentite

Answer : D

Question. Roasting of sulphides gives the gas X as a byproduct.
This is a colourless gas with choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic, acts as a reducing agent and its acid has never been isolated. The gas X is
(a) CO₂
(b) SO₃
(c) H₂S
(d) SO₂

Answer : D

Question. The metal oxide which cannot be reduced to metal by carbon is
(a) Al₂O₃
(b) PbO
(c) ZnO
(d) Fe₂O₃

Answer : A

Question. Which of the following pairs of metals is purified by van Arkel method?
(a) Ga and In
(b) Zr and Ti
(c) Ag and Au
(d) Ni and Fe

Answer : B

Question. The method of zone refining of metals is based on the principle of
(a) greater mobility of the pure metal than that of the impurity
(b) higher melting point of the impurity than that of the pure metal
(c) greater noble character of the solid metal than that of the impurity
(d) greater solubility of the impurity in the molten state than in the solid.

Answer : D

Question. Froth floatation is a process of:
(a) Oxidation
(b) Reduction
(c) Refining
(d) Concentration

Answer : D

Question. Which of the following elements is present as the impurity to the maximum extent in the pig iron?
(a) Manganese
(b) Carbon
(c) Silicon
(d) Phosphorus

Answer : B

Question. Identify the correct statement from the following :
(a) Wrought iron is impure iron with 4% carbon.
(b) Blister copper has blistered appearance due to evolution of CO₂.
(c) Vapour phase refining is carried out for Nickel by van Arkel method.
(d) Pig iron can be moulded into a variety of shapes.

Answer : D

Question. In metallurgical process of aluminium, cryolite is mixed with alumina in its molten state, because it
(a) decreases the amount of alumina
(b) oxidises the alumina
(c) increases the melting point of alumina
(d) decreases the melting point of alumina

Answer : D

Question. Sulfide ores are common for the metals
(a) Ag, Cu and Pb
(c) Ag, Cu and Sn
(b) Ag, Mg and Pb
(d) Al, Cu and Pb

Answer : A

Question. Calcium is obtained by
(a) reduction of calcium chloride with carbon
(b) electrolysis of molten anhydrous calcium chloride
(c) roasting of limestone
(d) electrolysis of solution of calcium chloride in H₂O.

Answer : B

Question. Extraction of gold and silver involves leaching with CN– ion. Silver is later recovered by
(a) distillation
(b) zone refining
(c) displacement with Zn
(d) liquation

Answer : C