Question

Auto-oxidation of bleaching powder gives:
(A).Only calcium chlorate
(B).Only calcium chloride
(C).Only calcium hypochlorite
(D).Both (a) and (b)

Answer 1

Bleach is a generic name for a chemical compound which is a substance which is used to remove stains or color in a process known as bleaching. It is a dilute solution of calcium hypochlorite having the chemical formula $Ca{{(ClO)}_{2}}$.

Complete answer:
Bleaching powder is a yellowish white color solid having a strong smell of chlorine. Bleaching powder is prepared on a large scale by passing chlorine gas through a solution of calcium hydroxide also known as slaked lime.
On long standing bleaching powder undergoes autoxidation and forms calcium chlorate and calcium chloride.
The reaction involves is mentioned below:
$CaOC{{l}_{2}}\to Ca{{(Cl{{O}_{3}})}_{2}}+CaC{{l}_{2}}$
The balanced chemical reaction is mentioned below:
$6CaOC{{l}_{2}}\to 6Ca{{(Cl{{O}_{3}})}_{2}}+5CaC{{l}_{2}}$

Hence the correct answer is option (D) i.e. both calcium chlorate and calcium chloride.

Additional information:
Bleaching powder is prepared by using a solution of slaked lime. The reaction involved is mentioned below:
$Ca{{(OH)}_{2}}+C{{l}_{2}}\to CaOC{{l}_{2}}+{{H}_{2}}O$
In this reaction one mole of calcium hydroxide reacts with one mole of chlorine and produces one mole of bleaching powder and one mole of water.
Bleaching powder is used as commercial bleach for wood pulp in oils and soaps as a disinfectant and germicide especially in the sterilization of drinking water and it is also used as an oxidizing agent in many chemical industries to obtain various products.

Note:
Bleaching powder is soluble in water but it does not form a clear solution due to the presence of the impurities. When bleaching powder reacts with carbon dioxide it forms calcium carbonate and chlorine as products.