In one of the industrial processes used for the manufacture of sodium hydroxide, a gas $X$ is formed as a by-product. The gas $X$ reacts with lime water to give a compound $Y$ which is used as a bleaching agent in the chemical industry. Identify $X$ and $Y$.

The correct option is B $X$ is chlorine; $Y$ is bleaching powder
Sodium chloride is used for manufacture of sodium hydroxide which is called chloralkali process. In this process chlorine and hydrogen gas are formed as byproducts along with sodium hydroxide. Chlorine gas gives bleaching power when reacts with lime water and used as bleaching agent in chemical industries.
$2NaCl\left(aq\right)+2H_{2}O\left(l\right)\to 2NaOH\left(aq\right)+C{l}_2\left(g\right)+H_2\left(g\right)$
$X\to C{l}_2$ (Chlorine gas)
$Ca(OH{)}_2+C{l}_2⟶CaOC{l}_2+H_{2}O$

Therefore,

• The gas $X$ is chlorine.
• Compound $Y$ is calcium oxychloride which is commonly known as bleaching powder and used as bleaching agent in chemical industries.