Chemistry · Practical Organic Chemistry

JEE Main 2025 — 3 April, Evening Shift — Question 9

In Dumas' method for estimation of nitrogen 0.4 g of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm Hg pressure. The percentage composition of nitrogen in the compound is (Given : Aqueous tension at $300 \mathrm{~K}=15 \mathrm{~mm} \mathrm{Hg}$ )

Option A:
$7.85 \%$
Option B:
$20.95 \%$
Option C:
$17.46 \%$
Option D:
$15.71 \%$
Correct

Answer: D

Step-by-step solution

$\mathrm{P}_{\mathrm{N}_{2}}=715-15=700 \mathrm{~mm} \mathrm{Hg}$

$n_{N_{2}}=\frac{P V}{R T}=\frac{700 \times 60}{760 \times 1000 \times 0.0821 \times 300}$

$\mathrm{n}_{\mathrm{N}_{2}}=2.24 \times 10^{-3}$

$\% \mathrm{~N}_{2}=\frac{2.24 \times 10^{-3} \times 28}{0.4} \times 100$

= $15.71 \%$

Answer key and solution verified before publishing.

Practise Practical Organic Chemistry

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Solve a similar one free

Exam: JEE Main 2025
Paper: 3 April, Evening Shift
Subject: Chemistry
Chapter: Practical Organic Chemistry
Topic: Quantitative organic analysis