The white precipitate (Y), obtained on passing colorless and odourless gas (X) through an ammoniacal solution of NaCl, losses about 37% of its weight on heating and a white residue (Z) of basic nature is left. Identify (X), (Y) and (Z) from following sets.

In the extraction of Ca by electro reduction of molten CaCl₂ some CaF₂ is added to the electrolyte for the following reason :

The compound, which evolves carbon dioxide on treatment with aqueous solution of sodium bicarbonate at 25$$^\circ$$C, is

The reactive species in chlorine bleach is