# MCQ Questions for Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements with Answers

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## General Principles and Processes of Isolation of Elements Class 12 MCQs Questions with Answers

Solve this General Principles and Processes of Isolation of Elements Multiple Choice Questions of Class 12 Chemistry Chapter 6 MCQ, so as not to miss out on any concept from being clear about what they mean!

Question 1.
Cinnabar is an ore of
(a) Hg
(b) Ag
(c) Sn
(d) Al

Question 2.
Pyrolusite is an ore of
(a) Ag
(b) Hg
(c) Sn
(d) Mn

Question 3.
Malachite is an ore of
(a) Hg
(b) Cu
(c) Sn
(d) Mn

Question 4.
The process employed for the concentration of sulphide ore is
(a) Froth floatation
(b) Roasting
(c) Electrolysis
(d) Calcination

Question 5.
Zone-refining is used for the
(a) concentration of an ore
(b) reduction of metal oxide
(c) purification of metal
(d) purification of an ore.

Question 6.
The metal always found in free state is
(a) Gold
(b) Silver
(c) Copper
(d) Sodium

Question 7.
Bauxite is an ore of
(a) Aluminium
(b) Calcium
(c) Copper
(d) Zinc

Question 8.
Most abundant element in earth’s crust is
(a) O
(b) Si
(c) Al
(d) Fe

Question 9.
Which of the following ores is concentrated by the froth floatation process?
(a) Haematite
(b) Magnetite
(c) Copper pyrite
(d) Bauxite

Question 10.
Common impurities present in bauxite ore:
(a) CuO
(b) ZnO
(c) Fe2O3
(d) None of these

Question 11.
In which of the following minerals Al is not present?
(a) Cryolite
(b) Mica
(c) Feldspar
(d) Fluorspar

Question 12.
In the metallurgy of iron from haematite, limestone is added to act as
(a) flux
(b) slag
(c) a reducing agent
(d) an oxidising agent

Question 13.
Purest form of iron is
(a) cast iron
(b) wrought iron
(c) steel
(d) pig iron

Question 14.
In the extraction of chlorine by electrolysis of brine
(a) oxidation of Cl ion to chlorine gas occurs.
(b) reduction of Cl ion to chlorine gas occurs.
(c) for overall reaction ΔGΘ has negative value.
(d) a displacement reaction takes place.

Answer: (c) for overall reaction ΔGΘ has negative value.

Question 15.
When copper ore is mixed with silica in a reverberatory furnace, copper matte is produced. The copper matte contains
(a) sulphides of copper (II) and iron (II)
(b) sulphides of copper (II) and iron (III)
(c) sulphides of copper (I) and iron (II)
(d) sulphides of copper (I) and iron (III)

Answer: (c) sulphides of copper (I) and iron (II)

Question 16.
Which of the following reactions is an example of auto reduction?
(a) Fe3O4 + 4C0 → 3Fe + 4CO2
(b) Cu2O + C → 2Cu + CO
(c) Cu2+(aq) + Fe(s) → Cu(s) + Fe2+(aq)
(d) Cu2O + $$\frac { 1 }{2}$$ Cu2S → 3Cu + $$\frac { 1 }{2}$$ SO2

Answer: (d) Cu2O + $$\frac { 1 }{2}$$ Cu2S → 3Cu + $$\frac { 1 }{2}$$ SO2

Question 17.
A number of elements are available in earth’s crust but most abundant elements are
(a) Al and Fe
(b) Al and Cu
(c) Fe and Cu
(d) Cu and Ag

Question 18.
Zone refining is based on the principle that
(a) impurities of low boiling metals can be separated by distillation.
(b) impurities are more soluble in molten metal than in solid metal.
(c) different components of a mixture are differently adsorbed on an adsorbent.
(d) vapours of volatile compound can be decomposed in pure metal.

Answer: (b) impurities are more soluble in molten metal than in solid metal.

Question 19.
In the extraction of copper from its sulphide ore, the metal is formed by the reduction of Cu2O with
(a) FeS
(b) CO
(c) Cu2S
(d) SO2

Question 20.
Brine is electrolysed by using inert electrodes. The reaction at anode is
(a) Cl (aq.) → $$\frac { 1 }{2}$$ Cl2 (g) + e; E$$_{ cell }^{Θ}$$ = 1.36 V
(b) 2H2O (l) → O2 (g) + 4H+ + 4e; E$$_{ cell }^{Θ}$$ = 1.23 V
(c) Na+ (aq.) + e → Na(s); E$$_{ cell }^{Θ}$$ = 2.71 V
(d) H+ (aq.) + e → $$\frac { 1 }{2}$$ H2 (g); E$$_{ cell }^{Θ}$$ = 0.00 V

Answer: (a) Cl (aq.) → $$\frac { 1 }{2}$$ Cl2 (g) + e; $$_{ cell }^{®}$$ = 1.36 V

Question 21.
In …………… the metallurgy of aluminium
(a) Al3+ is oxidised to Al (s).
(b) graphite anode is oxidised to carbon monoxide and carbon dioxide.
(c) oxidation state of oxygen changes in the reaction at anode.
(d) oxidation state of oxygen changes in the overall reaction involved in the process.

Answer: (b) graphite anode is oxidised to carbon monoxide and carbon dioxide.

Question 22.
Electrolytic refining is used to purify which of the following metals?
(a) Cu and Zn
(b) Ge and Si
(c) Zr and Ti
(d) Zn and Hg

Question 23.
Extraction of gold and silver involves leaching the metal with CN ion. The metal is recovered by
(a) displacement of metal by some other metal from the complex ion.
(b) roasting of metal complex.
(c) calcination followed by roasting.
(d) thermal decomposition of metal complex.

Answer: (a) displacement of metal by some other metal from the complex ion.

Answer the questions 24-26 on the basis of the figure given below:

Question 24.
Choose the correct option of temperature at which carbon reduces FeO to iron and produces CO.
(a) Below temperature at point A.
(b) Approximately at the temperature corresponding to point A.
(c) Above temperature at point A but below temperature at point D.
(d) Above temperature at point A.

Answer: (d) Above temperature at point A.

Question 25.
Below point ‘A’ FeO can
(a) be reduced by carbon monoxide only.
(b) be reduced by both carbon monoxide and carbon.
(c) be reduced by carbon only.
(d) not be reduced by both carbon and carbon monoxide.

Answer: (a) be reduced by carbon monoxide only.

Question 26.
For the reduction of FeO at the temperature corresponding to point D, which of the following statements is correct?
(a) ΔG value for the overall reduction reaction with carbon monoxide is zero.
(b) ΔG value for the overall reduction reaction with a mixture of 1 mol carbon and 1 mol oxygen is positive.
(c) ΔG value for the overall reduction reaction with a mixture of 2 mol carbon and 1 mol oxygen will be positive.
(d) ΔG value for the overall reduction reaction with carbon monoxide is negative.

Answer: (a) ΔG value for the overall reduction reaction with carbon monoxide is zero.

Assertion and Reason Type Questions

The questions given below consist of an assertion and a reason. Use the following key to choose the appropriate answer.
(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is correct, Reason (R) is wrong statement.
(d) Assertion (A) is wrong, but Reason (R) is correct statement.

Question 27.
Assertion: Oxide and carbonate ores are concentrated by froth floatation process.
Reason: In froth floatation, pine oil is used because it preferentially wets the ore particles.

Answer: (d) Assertion (A) is wrong, but Reason (R) is correct statement.

Question 28.
Assertion: Gold and platinum occur in native state.
Reason: Gold and platinum are expensive metals.

Answer: (b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).

Question 29.
Assertion: Aluminothermy is used for the extraction of Cr from Cr2O3.
Reason: Aluminium has a high melting point.

Answer: (b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).

Question 30.
Assertion: Titanium can be purified by Van Arkel process.
Reason: Titanium form volatile Til4 unstable compound.

Answer: (a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).

Question 31.
Assertion: In Mond process, nickel is heated in a stream of CO forming a volatile complex.
Reason: This is an electrolytic refining method.