Question

Substance A is yellowish-white in colour and releases chlorine gas on reaction with dilute hydrochloric acid. The substance A is _______.

• A. common salt
• B. washing soda
• C. baking soda
• D. bleaching powder

Answer 1

The correct option is D bleaching powder

Bleaching powder with chemical name calcium oxychloride (${\text{CaOCl}}_2$) has yellowish-white colour. It releases chlorine gas on reaction with dilute hydrochloric acid ($\text{HCl}$) and sulphuric acid (${\text{H}}_2{\text{SO}}_4$). The reactions are given below:

${\mathrm{CaOCl}}_2\left(s\right)+H_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{CaSO}}_4\left(s\right)+{\mathrm{Cl}}_2\left(g\right)+H_{2}O\left(l\right)$
${\mathrm{CaOCl}}_2\left(s\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{CaCl}}_2\left(s\right)+{\mathrm{Cl}}_2\left(g\right)+H_{2}O(l{)}^{}$