Match the compound in List I with the statement in List II. List I: (P) $CaCO X_{3}$ ; (Q) $Ca (OH) X_{2}$ ; (R) $NaHCO X_{3}$ ; (S) $CaSO X_{4} \cdot 2 H X_{2} O$ . List II: (1) loses mass near 400 K, releasing both $CO X_{2}$ and steam; (2) decomposes only near 1100 K to a basic oxide and $CO X_{2}$ ; (3) its clear aqueous solution turns milky on passing a little $CO X_{2}$ ; (4) on heating to 393 K gives a solid that sets to a hard mass with water.

Answer: A

CaCO X_{3} CaO + CO X_{2}

needs about 1100 K (P-2). Lime water, a solution of

Ca (OH) X_{2}

, turns milky with

CO X_{2}

(Q-3).

NaHCO X_{3}

gives

CO X_{2}

and

H X_{2} O

near 400 K (R-1). Gypsum gives plaster of Paris at 393 K, which sets with water (S-4).