Represent the addition of dilute sulphuric acid to zinc by means of a chemical equation. State the function of the arrow between the reactants and products.

A chemical reaction is generally accompanied by certain external indications or characteristics. These include change of –

(a) color

(b) state

(c) smell

(d) evolution of gas

(e) formation of precipitate

(f) evolution or absorption of heat.

With reference to change of color – state the change in color seen when the following are heated –

(i) copper carbonate

(ii) zinc carbonate

(iii) mercury [II] oxide

(iv) lead [IV] oxide

In certain reactions a change of smell is observed. Give two examples from daily life of the same.