Question

solution of a substance X is used for whitewashing name the substance substance X and give reason

Answer 1

The substance ‘X’ is calcium oxide. Its chemical formula is CaO.
Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).

CaO (s)+ H2O (l) → Ca(OH)2 (aq)

Answer 2

The substance 'X' used for whitewashing is quick lime(calcium oxide).its formula is CaO.
CaO(s) + H20(l) ---- Ca(OH)2(aq) + heat