Chemical reactivity of elements depends on the ease with which it attains electronic configuration of the nearest inert gas by gaining or losing electrons.
The elements preceding an inert gas react...
(1) (a) ammonia is less dense than air
(b) solubility in water
(c) 2NH3 + H2SO4 → (NH4)2SO4
(2) (a) Ammonia → because - NH3 is basic while, SO2,HCl and CO2 are acidic oxides.
(b) CuO,...