Fused alumina is reduced to aluminium by electrolytic reduction, since:

1. alumina is highly stable.
2. alumina is least stable.
3. alumina is not reduced by drying agents.
4. alumina is not reduced by reducing agents.

The chemical name of the principal ore of aluminium is:

1. sodium aluminium fluoride
2. aluminium oxide
3. hydrated aluminium fluoride
4. hydrated aluminium oxide

Steel is an alloy of iron and:

1. Nickel
2. Zinc
3. Carbon
4. Aluminium

The reason for using aluminium in the alloy duralumin is

1. Aluminium is brittle.
2. Aluminium gives strength.
3. Aluminium brings lightness.
4. Aluminium lowers melting point.