P1 = 715 – 15 = 700mm Hg, P1 = 760 mm Hg
\(\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}\)
T1 = 300 K, T2 = 273 K, V1 = 50 cm3, V2 = ?
V2 = \(\frac{700\times50\times273}{300\times760}\) = 41.9 cm3
% of N = \(\frac{28}{22400}\) x 41.9 x \(\frac{100}{W}\) = 17.46%