Convert the following reactions into a balanced chemical equation:

(a) Ammonia to nitric oxide using oxygen and platinum catalyst.

$4\text{NH}_3 + 5\text{O}_2 \xrightarrow[800 ^{\circ} \text{C}]{\text{Pt}.} 4\text{NO} + 6\text{H}_2\text{O} + \Delta$

(b) Sodium hydroxide to sodium sulphate using sulphuric acid.

2NaOH + H₂SO₄ ⟶ Na₂SO₄ + 2H₂O

(c) Ferrous sulphide to hydrogen sulphide using hydrochloric acid

FeS + 2HCl ⟶ FeCl₂ + H₂S