A pair of metals that can be purified by van Arkel method is:

1. Zr and Ti

2. Ag and Au

3. Ni and Fe

4. Ga and In

Sulphide ores of metals are usually concentrated by the froth flotation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?

1. Argentite

2. Galena

3. Copper pyrite

4. Sphalerite

Which one is a malachite from the following?

1. CuCO₃.Cu(OH)₂

2. CuFeS₂

3. Cu(OH)₂

4. Fe₃O₄

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

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

1. Copper(l) sulphide (Cu₂S)

2. Sulphur dioxide (SO₂)

3. Iron Sulphide (FeS)

4. Carbon monoxide (CO)

Which one of the following is a mineral of iron?

1. Malachite

2. Cassiterite

3. Pyrolusite

4. Magnetite

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

1. ${\mathrm{Al}}_2{\mathrm{O}}_3+\mathrm{HF}+{\mathrm{NaAlF}}_4$

2. ${\mathrm{Al}}_2{\mathrm{O}}_3+{\mathrm{CaF}}_2+{\mathrm{NaAlF}}_4$

3. ${\mathrm{Al}}_2{\mathrm{O}}_3+{\mathrm{Na}}_3{\mathrm{AlF}}_6+{\mathrm{CaF}}_2$

4. ${\mathrm{Al}}_2{\mathrm{O}}_3+\mathrm{KF}+{\mathrm{Na}}_3{\mathrm{AlF}}_6$

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

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