Complete the following 'word' equations. Write the words 'No reaction' if none occurs.

(a) magnesium + copper sulphate ⟶

(b) iron (II) sulphide + hydrochloric acid ⟶

Write the equation for the following and state whether it is a decomposition reaction : The action of heat on lead nitrate.

(a) What is meant by the term 'atomicity of a gas'?

(b) Name a gas that is diatomic.

Name a common substance that exists in all the three states of matter.