At $$760\,torr$$ pressure and $${20^ \circ }C$$ temperature, $$1\,L$$ of water dissolves $$0.04\,gm$$ of pure oxygen or $$0.02\,gm$$ of pure nitrogen. Assuming that dry air is composed of $$20\% $$ oxygen and $$80\% $$ nitrogen
(by volume), the masses ( in $$g/L$$ ) of oxygen and nitrogen dissolved by $$1\,L$$ of water at $${20^ \circ }C$$ exposed to air at a total pressure of $$760\,torr$$ are respectively :