Question

Assertion :Chlorine water must be stored in dark colored bottles. Reason: Hypochlorous acid on exposure to sunlight decomposes to $H_2$ and $C{l}_2$ gas.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

The correct option is C Assertion is correct but Reason is incorrect.

Chlorine degrades quickly when exposed to light or organic matter. Brown or other dark bottles are used for its storage to protect it from light. Generally, anything stored in a dark colored or opaque container is light sensitive.
Hypochlorous acid in solution is pale golden yellow, or colourless when dilute. It is 0.02 per cent, ionised in $N/10$ solution. The dilute solution is fairly stable in the dark: concentrated solutions; decompose on heating or exposure to sunlight, with evolution of oxygen and chlorine and formation of some chloric acid.

1. $2HOCl\to 2HCl+O_2$
2. $HCl+HOCl\to H_{2}O+C{l}_2$
3. $HOCl+2O\left(nascent\right)\to HCl{O}_3$

Thus Option C is correct.