Write the molecular formula of:

(a) Sodium sulphide

(b) Magnesium oxide

(c) Calcium hydroxide

(d) Hydrogen chloride

(e) Sulphuric acid

(f) Iron (II) sulphide

(g) Iron (III) sulphate

(h) Nitric acid

(i) Calcium phosphate

(j) Aluminium sulphate

(k) Magnesium nitride

The valency of sodium is one. Write the molecular formula for the following compounds of sodium.

(a) sodium oxide

(b) sodium sulphate

(c) sodium carbonate

(d) sodium hydroxide

(e) sodium nitrate

Give the group number of the following elements present in periodic table.

(a) Magnesium

(b) Carbon

(c) Sulphur

(d) Neon

An element belongs to group VA. What would be its valency? Name two such elements.