Some chemical substances are given below. From these, find out the substances required for the preparation of nitrogen and hydrogen, in the laboratory.

Sulphuric acid, hydrochloric acid, sodium nitrite, zinc, potassium permanganate, ammonium chloride, water.

Preparing nitrogen (N₂) in laboratory:

Heating a mixture of sodium nitrite and ammonium chloride gives ammonium nitrite (NH₄NO₂) which is highly unstable.

NaNO₂ + NH₄Cl → NH₄NO₂ + NaCl

Ammonium chlorate readily decomposes to give nitrogen gas.

NH₄NO₂→ N₂ + 2H₂O

Preparing hydrogen (H₂) in the laboratory:

a) Zinc (Zn) when treated with sulphuric acid (H₂SO₄) liberates hydrogen gas.

Zn + H₂SO₄→ ZnSO₄ + H₂

b) Zinc when treated with hydrochloric acid (HCl) also liberates hydrogen gas.

Zn + 2HCl → ZnCl₂ + H₂

c) Water upon electrolysis gives hydrogen and oxygen. Electrolysis is the process of decomposition produced when an electric current is passed through a solution.