Explan the following :
(i) Concentrated `HNO_3` turns yellow in sunlight.
(ii) Bleaching powder loses its bleaching property when it is kept in an open bottle for a long lime.

Explanation

(i) `2 HNO_3 rarr H_2 O + 2 NO_2 + (1)/(2) O_2`
In sunlight, slight decomposition of nitric acid produces nitrogen dioxide which is brown in colour. It dissolves in nitric acid to give pale yellow colour.
(ii) `CaOCl_2 + H_2 O rarr Ca(OH)_2 + Cl_2`
In the presence of moisture, bleaching powder loses chlorine, so its bleaching action decreases.