Question

All dilute acids react with bleaching powder liberating
A. Chlorine gas
B. Hydrogen gas
C. Nitrogen gas
D. $HCl$ gas

Answer 1

Bleaching powder is calcium oxychloride. The common name for bleaching powder is chloride of lime. The chemical formula of bleaching powder is $CaOC{l_2}$. It is white powder soluble in water and has a strong smell like chlorine gas.

Complete answer:

Bleaching powder is also known as calcium oxychloride with the formula $CaOC{l_2}$ .
Bleaching powder is manufactured by using slaked lime and chlorine gas. Slaked lime is the common name for calcium hydroxide. The reaction is as follows-
$2Ca{(OH)_2} + 2C{l_2} \to CaC{l_2} + CaOC{l_2} + {H_2}O$
When bleaching powder is treated with excess of dilute acid, chlorine gas is liberated.
For example, when bleaching powder is treated with dilute sulphuric acid, calcium sulphate and water is formed and chlorine gas is liberated. The reaction is as follows-
$CaOC{l_2} + {H_2}S{O_4} \to CaS{O_4} + C{l_2} + {H_2}O$
Chlorine gas produced by the action of dilute acid on bleaching powder acts as a bleaching agent.

So, the correct option is A.

Additional information:

Bleaching powder is used for bleaching in the textile industry, for bleaching pulpwood in paper factories and for washed clothes in industry.
It is also used as an oxidizing agent in chemical industries and used to make drinking water free of germs. It is commonly used to disinfect water in swimming pools.
It is also used to manufacture chloroform.

Note: Bleaching powder is made with moist slaked lime. It is basic in character. It also releases chlorine gas when it reacts with carbon-dioxide. Bleaching powder can undergo auto-oxidation into calcium chlorate and calcium chloride if left unused for a long period of time. It has oxidizing character due to the presence of nascent oxygen.