How is bleaching powder prepared? Why does bleaching powder $(i)$ smell strongly of chlorine?

(N/A) Bleaching powder is prepared by the action of chlorine gas $(Cl_2)$ on dry slaked lime $[Ca(OH)_2]$.
The chemical reaction is:
$Ca(OH)_2 + Cl_2 \to CaOCl_2 + H_2O$
Bleaching powder smells strongly of chlorine because it reacts with carbon dioxide $(CO_2)$ present in the atmosphere,which leads to the liberation of free chlorine gas.