MHTCET 18 Apr 2026 Shift 2 Paper

Concept:For gases in a mixture at the same temperature and volume, partial pressure is directly proportional to the number of moles.Explanation:Assume the total mass of the mixture is $100$ g.Mass of helium is $20\%$ of $100$ g, so $m_{\mathrm{He}} = 20$ g.Therefore, mass of neon is $m_{\mathrm{Ne}} = 100 - 20 = 80$ g.Molar mass of He is $4 \ \mathrm{g\,mol}^{-1}$.Moles of He: $n_{\mathrm{He}} = \frac{20}{4} = 5$ mol.Molar mass of Ne is $20 \ \mathrm{g\,mol}^{-1}$.Moles of Ne: $n_{\mathrm{Ne}} = \frac{80}{20} = 4$ mol.At the same temperature and volume, $P \propto n$.So, $P_{\mathrm{He}} : P_{\mathrm{Ne}} = n_{\mathrm{He}} : n_{\mathrm{Ne}} = 5 : 4$.Answer:The ratio of partial pressure of Helium to Neon is $5 : 4$.Correct option: C.