What is the mole fraction of water in 10 \% by weight ( w / w ) of aqueous urea solution ?[0pt][Given : Molar mass of H , O , C and N are 1, 16, 12 and 14 g mol -1 respectively]

Chemistry · Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry

JEE Main 2026 — 5 April, Morning Shift — Question 52

What is the mole fraction of water in $10 \%$ by weight $(\mathrm{w} / \mathrm{w})$ of aqueous urea solution ?[0pt][Given : Molar mass of $\mathrm{H}, \mathrm{O}, \mathrm{C}$ and N are 1, 16, 12 and $14 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively]

Option A:
0.825
Option B:
0.032
Option C:
0.867
Option D:
0.967
Correct

Answer: D

Step-by-step solution

Mass ratio $=$ mol ratio × GMM ratio $\frac{10}{90}=\frac{\mathrm{n}}{\mathrm{N}} \times \frac{60}{18}$ $\frac{\mathrm{n}}{\mathrm{N}}=\frac{1}{30}$ $\mathrm{x}_{\mathrm{H}_{2} \mathrm{O}}=\frac{\mathrm{W}}{\mathrm{n}+\mathrm{N}}=\frac{30}{31}=0.967$

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Exam: JEE Main 2026
Paper: 5 April, Morning Shift
Subject: Chemistry
Chapter: Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry
Topic: Concentration Terms and Their Interconversion

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Step-by-step solution

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