(a)
(i) It is used in the building material in the form of mortar.
(ii) It is used in the manufacture of bleaching powder.
(iii) It is used in glass making and the purification of sugar.
(iv) It is used to absorbed acidic gases.
(b)
1. NH4Cl + NaOH → NaCl + NH4OH
2. 2NaOH + CO2 → Na2CO3 + H2O