Question

A solution of a substance 'X' is used for whitewashing.
(i) Name the substance 'X' and write its formula.
(ii) Write the reaction of the substance 'X' named in (i) above with water.

Answer 1

(i) The substance 'X' used for whitewashing is quick lime (calcium oxide). Its formula is CaO.

(ii) When quick lime is mixed with water, the following reaction takes place:
              CaO(s) + H₂O(l) ------> Ca(OH)₂(aq) + Heat
(Quick lime calcium oxide)    water    calcium hydroxide(slaked lime)