Match List-I with List-II for the compositions of substances and select the correct answer using the code given above.

List-I (Substances)		List-II (Composition)
(A)	Plaster of Pairs	(i)	CaSO4$$ \cdot $$2H2O
(B)	Epsomite	(ii)	CaSO4$$ \cdot $$1/2 H2O
(C)	Kieserite	(iii)	MgSO4$$ \cdot $$7H2O
(D)	Gypsum	(iv)	MgSO4$$ \cdot $$H2O
		(v)	CaSO4

Which of the following compounds has the lowest melting point?

Which one of the following is present as an active ingredient in bleaching powder for bleaching action?

The compound A on heating gives a colourless gas and a residue that is dissolved in water to obtain B. Excess of CO₂ is bubbled through aqueous solution of B, C is formed which is recovered in the solid form. Solid C on gentle heating gives back A. The compound is