Q 11-12-101JEE MainJEE Main 2021 (31 Aug, Shift 2)Medium
A mixture of hydrogen and oxygen has volume $500\ \text{cm}^3$, temperature $300$ K, pressure $400$ kPa and mass $0.76$ g. The ratio of masses of oxygen to hydrogen will be:
Answer: (A) $16 : 3$
Total moles: $n = \dfrac{PV}{RT} = \dfrac{4\times10^5\times5\times10^{-4}}{8.314\times300} \approx 0.08$ mol.
$n_H + n_O = 0.08$ and $2n_H + 32n_O = 0.76$ (grams).
Solving: $30n_O = 0.60 \Rightarrow n_O = 0.02$, $n_H = 0.06$.
Masses: oxygen $0.64$ g, hydrogen $0.12$ g, ratio $= 16 : 3$.
Solution by Sreeraj P, M.Sc Physics