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 balanced equations for the following reactions of synthesis involving formation of :

(a) An acid – from sulphur dioxide gas

(b) An alkali – from a basic oxide – sodium oxide

(c) A salt – from a trivalent metal and a coloured gas.