The reaction of NO with N₂O₄ at 250 K gives :

Match the following compounds (Column-I) with their uses (Column-II) :

S.No.	Column-I	S.No.	Column-II
(I)	Ca(OH)2	(A)	casts of statues
(II)	NaCl	(B)	white wash
(III)	CaSO4, $${1 \over 2}$$H2O	(C)	antacid
(IV)	CaCO3	(D)	washing soda preparation

The IUPAC name of the following compound is :

Reaction of an inorganic sulphite X with dilute H₂SO₄ generates compound Y. Reaction of Y with NaOH gives X. Further, the reaction of X with Y and water affords compound Z. Y and Z, respectively, are :