Chemistry · States of Matter - Gaseous State

JEE Main 2025 — 7 April, Morning Shift — Question 8

At the sea level, the dry air mass percentage composition is given as nitrogen gas: 70.0, oxygen gas: 27.0 and argon gas: 3.0. If total pressure is 1.15 atm , then calculate the ratio of following respectively:

(i) partial pressure of nitrogen gas to partial pressure of oxygen gas

(ii) partial pressure of oxygen gas to partial pressure of argon gas

(Given: Molar mass of N, O and Ar are 14, 16 and $40 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively.)

Option A:
$2.59,11.85$
Option B:
$5.46,17.8$
Option C:
$2.96,11.2$
Correct
Option D:
$4.26,19.3$

Answer: C

Step-by-step solution

\begin{aligned} & \mathrm{p}_{\mathrm{O}_{2}}=\frac{\frac{27}{32}}{\frac{27}{32}+\frac{70}{28}+\frac{3}{40}} \times 1.15 \mathrm{~atm} \\& \mathrm{p}_{\mathrm{N}_{2}}=\frac{\frac{70}{28}}{\frac{27}{32}+\frac{70}{28}+\frac{3}{40}} \times 1.15 \mathrm{~atm} \\& \mathrm{p}_{\mathrm{Ar}}= \frac{\frac{3}{40}}{\frac{27}{32}+\frac{70}{28}+\frac{3}{40}} \times 1.15 \mathrm{~atm} \\& \frac{\mathrm{p}_{\mathrm{N}_{2}}}{\mathrm{p}_{\mathrm{O}_{2}}}=2.95 \\& \frac{\mathrm{p}_{\mathrm{O}_{2}}}{\mathrm{p}_{\mathrm{Ar}^{2}}}=11.18 \end{aligned}

Answer key and solution verified before publishing.

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Exam: JEE Main 2025
Paper: 7 April, Morning Shift
Subject: Chemistry
Chapter: States of Matter - Gaseous State
Topic: Measurable Properties of Gases and Basic Gas Laws