At 1 atmospheric pressure and $$0{\,^ \circ }C,$$  certain mass of a gas measures $$0.4\,L.$$  Keeping the pressure constant, if the temperature is increased to $$273{\,^ \circ }C,$$  what will be its volume ?

Solution :
$$\eqalign{ & \frac{{{P_1}{V_1}}}{{{T_1}}} = \frac{{{P_2}{V_2}}}{{{T_2}}} \cr & \Rightarrow \frac{{1 \times 0.4}}{{273}} = \frac{{1 \times {V_2}}}{{546}} \cr & {V_2} = \frac{{1 \times 0.4 \times 546}}{{273 \times 1}} = 0.8\,L \cr} $$