Q 11-12-032JEE MainJEE Main 2026 (2 Apr, Shift 2)Medium
A mixture of carbon dioxide and oxygen has volume $8310\ \text{cm}^3$, temperature $300$ K, pressure $100$ kPa and mass $13.2$ g. The number of moles of carbon dioxide and oxygen gases in the mixture respectively are ______.
(Assume both carbon dioxide and oxygen gases behave like ideal gases) [$R=8.31$ J/mol K]
Answer: (C) $0.21$ and $0.12$
Total moles: $n=\dfrac{PV}{RT}=\dfrac{10^{5}\times8310\times10^{-6}}{8.31\times300}=\dfrac13$ mol.
Let $x$ = moles of CO$_2$ (44 g/mol) and $y$ = moles of O$_2$ (32 g/mol):
$x+y=\tfrac13,\qquad44x+32y=13.2$
$44x+32\left(\tfrac13-x\right)=13.2\Rightarrow12x=13.2-10.67=2.53\Rightarrow x\approx0.21$, $y\approx0.12$.
Solution by Sreeraj P, M.Sc Physics