(i) Why is it necessary to compare gases at STP ?

(ii) What are the STP conditions ?

What temperature in degree centigrade would be necessary to double the volume of a gas (initially at STP), if the pressure is reduced to half ?

Mohr's salt has the formula (NH₄)₂SO₄.FeSO₄.6H₂O

(i) Calculate its molecular mass.

(ii) What is the percentage of Nitrogen in Mohr's salt ? (Atomic mass: N =14, H = 1, S = 32, Fe = 56, O = 16)

Write balanced chemical equations for the preparation of Hydrogen, when the following are used :

(i) Alkali

(ii) Non metal