General Principles of Isolation of Elements · Question 7

Considering Ellingham diagram, which of the following metals can be used to reduce alumina?

1. Fe
2. Zn
3. Mg
4. Cu

Extraction of gold and silver involves leaching with CN- ion. Silver is later recovered by

1. distillation
2. zone refining
3. displacement with Zn
4. liquation

Match items of Column I with the items of Column II and assign the correct code :

1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(iii), (b)-(iv), (c)-(v), (d)-(i)
3. (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
4. (a)-(ii), (b)-(iii), (c)-(i), (d)-(v)

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with

1. carbon monoxide
2. copper (I) sulphide
3. sulphur dioxide
4. iron (II) sulphide

"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.

1. I is false but II is true.
2. I is true but II is false.
3. I and II are true.
4. I and II are false

The metal oxide which cannot be reduced to metal by carbon is

1. Al2O3
2. PbO
3. ZnO
4. Fe2O3

The Gibbs energy for the decomposition of Al2O3 at 500 is as follows 23Al2O3 43Al + O2 rG = +960 kJ mol-1 The potential difference needed for the electrolytic reduction of aluminium oxide (Al2O3) at 500 is at least

1. 4.5 V
2. 3.0 V
3. 2.5 V
4. 5.0 V

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with

1. carbon monoxide
2. copper (I) sulphide
3. sulphur dioxide
4. iron (II) sulphide.

Aluminium is extracted from alumina (Al2O3) by electrolysis of a molten mixture of

1. Al2O3 + HF + NaAlF4
2. Al2O3 + CaF2 + NaAlF4
3. Al2O3 + Na3AlF6 + CaF2
4. Al2O3 + KF + Na3AlF6

Which one of the following is a mineral of iron?

1. Malachite
2. Cassiterite
3. Pyrolusite
4. Magnetite