Describe two important uses of each of the following: $(i)$ caustic soda,$(ii)$ sodium carbonate,$(iii)$ quicklime.

(N/A) $(i)$ Uses of caustic soda:
$(a)$ It is used in the soap industry.
$(b)$ It is used as a reagent in the laboratory.
$(ii)$ Uses of sodium carbonate:
$(a)$ It is generally used in the glass and soap industry.
$(b)$ It is used as a water softener.
$(iii)$ Uses of quicklime:
$(a)$ It is used as a starting material for obtaining slaked lime.
$(b)$ It is used in the manufacture of glass and cement.