State one example of a reaction characterised by change in temperature.

Write balanced chemical equation for the following reaction.

Sodium hydroxide solution is heated with granulated zinc.

You are given the following materials:

(i) Marble chips (ii) Dilute hydrochloric acid (iii) Zinc granules.

(a) Write a balanced chemical equation for the reaction involved.
(b) What other name is given to the precipitation reaction
(c) On adding dilute hydrochloric acid to the reaction mixture, the precipitate disappears. Why?

Balance the following chemical equations and identify the type of reaction involved.

${\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)+\mathrm{}{\mathrm{O}}_2\left(\mathrm{g}\right)\mathrm{}\to \mathrm{S}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$