Match List I with List II
(A) Slaked lime                                     (I) $\mathrm{NaOH}$
(B) Dead burnt plaster                          (II) $\mathrm{Ca}(\mathrm{OH}{)}_2$
(C) Caustic soda                                  (III) ${\mathrm{Na}}_2{\mathrm{CO}}_3·10{\mathrm{H}}_2\mathrm{O}$
(D) Washing soda                                 (IV) ${\mathrm{CaSO}}_4$
Choose the correct answer form the options given below:

(A) Slaked lime: Calcium oxide is a white amorphous solid. It has a melting point of 2870 K. On exposure to the atmosphere, it absorbs moisture and carbon dioxide. 

$\mathrm{CaO} + {\mathrm{H}}_2\mathrm{O} \to \mathrm{Ca}(\mathrm{OH}{)}_2$

$\mathrm{CaO} + {\mathrm{CO}}_2 \to {\mathrm{CaCO}}_3$

The addition of a limited amount of water breaks the lump of lime. This process is called slaking of lime.

(B) Dead burnt plaster: Calcium sulphate is a hemihydrate of calcium sulphate. It is obtained when gypsum, ${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$ is heated at 393K.

$2({\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}) \to 2\left({\mathrm{CaSO}}_4\right).{\mathrm{H}}_2\mathrm{O} + 3{\mathrm{H}}_2\mathrm{O}$

Above 393 K, no water of crystallisation is left and anhydrous calcium sulphate, ${\mathrm{CaSO}}_4$ is formed. This is known as ‘dead burnt plaster’.

(C) Caustic soda: Sodium hydroxide (caustic soda) $\mathrm{NaOH}$ is generally prepared commercially by the electrolysis of sodium chloride in Castner-Kellner cell. A brine solution is electrolysed using a mercury cathode and a carbon anode. Sodium metal discharged at the cathode combines with mercury to form sodium amalgam.

(D) Washing soda: Sodium carbonate is a white crystalline solid which exists as a decahydrate, ${\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}$. This is also called washing soda. It is readily soluble in water.

So, the correct matching is (A)-II, (B)-IV, (C)-I, (D)-III.