Roasting of sulphides gives the gas X as a by-product. This is a colourless gas with a choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic and  acts as an oxidizing agent and its acid has never been isolated. The gas X is:

1. SO₂

2. CO₂

3. SO₃

4. H₂S

Which one of the following is a mineral of iron?

1. Malachite

2. Cassiterite

3. Pyrolusite

4. Magnetite

An interstitial compound among the following is:

1. Invar

2. Steel

3. Bell metal

4. Bronze

Which of the following elements is present as an impurity to the maximum extent in the pig Iron?
1. Carbon
2. Silicon
3. Phosphorus
4. Manganese

Which one is a malachite from the following?

1. CuCO₃.Cu(OH)₂

2. CuFeS₂

3. Cu(OH)₂

4. Fe₃O₄

"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? 

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

1. Iron(II) sulphide

2. Carbon monoxide

3. Copper(I) sulphide

4. Sulphur dioxide

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

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