Question

Bleaching powder slowly loses its activity when it stands in air. This is due to :

• A. reaction with water to evolve $O_2$
• B. reaction with $H_{2}O$ to evolve $H_2$
• C. loss of available chlorine
• D. formation of calcium hydroxide

Answer 1

The correct option is C loss of available chlorine

Bleaching action of bleaching powder is because of its chlorine. But when it comes in contact with air for a long time it loses its available chlorine.

$6CaOC{l}_2\to 6Ca(Cl{O}_3{)}_2+5CaC{l}_2$
Due to the loss of available chlorine, it loses its activity.