Give balanced equations for reactions involving evolution of a gas on addition of dilute acid to :

(a) sodium sulphite

(b) calcium carbonate

Give a balanced equation for conversion of:

(a) an ammonium salt to a basic gas

(b) a soluble lead salt to an insoluble lead salt – formed as a white precipitate.

Define the following types of chemical changes or reactions with a suitable example of each.

(a) Direct combination reaction or synthesis

(b) Decomposition reaction

(c) Displacement reaction or substitution reaction

(d) Double decomposition reaction

Give a balanced equation for a direct combination reaction involving :

(a) Two elements — one of which is a neutral gas and the other a yellow non-metal

(b) Two elements – one of which is a neutral gas and the other a monovalent metal

(c) Two compounds – resulting in formation of a weak acid