Chemistry 12 Chapter 6 General Principles and Processes of Isolation of Elements Part 1

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I. Multiple Choice Questions (Type-I)

Question 1:

In the extraction of chlorine by electrolysis of brine ____________.

(i) Oxidation of ion to chlorine gas occurs.

(ii) Reduction of ion to chlorine gas occurs.

(iii) For overall reaction has negative value.

(iv) A displacement reaction takes place.

Answer: (iii)

Question 2:

When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains ____________.

(i) Sulphides of copper (II) and iron (II)

(ii) Sulphides of copper (II) and iron (III)

(iii) Sulphides of copper (I) and iron (II)

(iv) Sulphides of copper (I) and iron (III)

Answer: (iii)

Question 3:

Which of the following reactions is an example of auto reduction?

(i)

(ii)

(iii)

(iv)

Answer: (iv)

Question 4:

A number of elements are available in earth’s crust but most abundant elements are ____________.

(i) and

(ii) and

(iii) and

(iv) and

Answer: (i)

Question 5:

Zone refining is based on the principle that ___________.

(i) Impurities of low boiling metals can be separated by distillation.

(ii) Impurities are more soluble in molten metal than in solid metal.

(iii) Different components of a mixture are differently adsorbed on an adosrbent.

(iv) Vapours of volatile compound can be decomposed in pure metal.

Answer: (ii)

Question 6:

In the extraction of copper from its sulphide ore, the metal is formed by the reduction of with

(i)

(ii)

(iii)

(iv)

Answer: (iii)

Question 7:

Brine is electrolysed by using inert electrodes. The reaction at anode is ________.

(i)

(ii)

(iii)

(iv)

Answer: (i)

Question 8:

In the metallurgy of aluminium ________________.

(i) is oxidized to

(ii) Graphide anode is oxidised to carbon monoxide and carbon dioxide.

(iii) Oxidation state of oxygen changes in the reaction at anode.

(iv) Oxidation state of oxygen changes in the overall reaction involved in the process.

Answer: (ii)

Question 9:

Electrolytic refining is used to purify which of the following metals?

(i)

(ii)

(iii)

(iv)

Answer: (i)

Question 10:

Extraction of gold and silver involves leaching the metal with CN – ion. The metal is recovered by ________________.

(i) Displacement of metal by some other metal from the complex ion.

(ii) Roasting of metal complex.

(iii) Calcination followed by roasting.

(iv) Thermal decomposition of metal complex.

Answer: (i)

Note: Answer the questions 11-13 on the basis of Fig. 6.1.

Temperature at which carbon reduces

Temperature at Which Carbon Reduces

Question 11:

Choose the correct option of temperature at which carbon reduces to iron and produces CO.

(i) Below temperature at point A.

(ii) Approximately at the temperature corresponding to point A.

(iii) Above temperature at point A but below temperature at point D.

(iv) Above temperature at point A.

Answer: (iv)

Question 12:

Below point ‘A’ can ______________.

(i) Be reduced by carbon monoxide only.

(ii) Be reduced by both carbon monoxide and carbon.

(iii) Be reduced by carbon only.

(iv) Not be reduced by both carbon and carbon monoxide.

Answer: (i)

Question 13:

For the reduction of at the temperature corresponding to point D, which of the following statements is correct?

(i) value for the overall reduction reaction with carbon monoxide is zero.

(ii) value for the overall reduction reaction with a mixture of carbon and oxygen is positive.

(iii) value for the overall reduction reaction with a mixture of carbon and oxygen will be positive.

(iv) value for the overall reduction reaction with carbon monoxide is negative.

Answer: (i)

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