$21.$ Which process is used to convert calcium hydroxide and chlorine gas to bleaching powder?

$-$ a$)$ Solvay process

$-$ b$)$ Hooker process

$-$ c$)$ Weldon process

$-$ d$)$ Deacon process

$23.$ What is the role of sodium carbonate in water softening?

$-$ a$)$ To increase hardness

$-$ b$)$ To precipitate calcium and magnesium ions

$-$ c$)$ To oxidize organic impurities

$-$ d$)$ To neutralize acids