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

1. Al₂O₃
2. PbO
3. ZnO
4. Fe₂O₃

The following reactions take place in the blast furnace in the preparation of impure iron.
Identify the reaction pertaining to the formation of the slag.

1. 2C(s) + O₂(g) → 2CO (g)
2. Fe₂O₃(s) + 3CO (g) → 2Fe(l) + 3CO₂(g)
3. CaCO₃(s) → CaO(s) + CO₂(g)
4. CaO(s) + SiO₂(s) → CaSiO₃(s)

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

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

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

An interstitial compound among the following is:

1. Invar

2. Steel

3. Bell metal

4. Bronze

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