$30.$ Which gas is produced at the cathode during the electrolysis of brine?

$-$ a$)$ Oxygen

$-$ b$)$ Chlorine

$-$ c$)$ Hydrogen

$-$ d$)$ Carbon dioxide

$31.$ Which compound forms when chlorine reacts with water in bleaching powder production?

$-$ a$)$ Hydrochloric acid

$-$ b$)$ Calcium hypochlorite

$-$ c$)$ Sodium hypochlorite

$-$ d$)$ Calcium chloride