Question
What is the mole fraction of water in 10% by weight (w/w) of aqueous urea solution? [Given: Molar mass of H, O, C and N are 1, 16, 12 and 14 g mol^ -1 respectively.]
JEE Main
Chemistry
Solutions
2026
JEE Main 2026 (05 April Shift 1)
JEE Main Chemistry Question (2026) — Solution
Options
- A. 0.825
- B. 0.032
- C. 0.867
- D. 0.967
Answer
D. 0.967
Step-by-step solution
10\% w/w aqueous urea solution means 10 g of urea is present in 100 g of solution. Mass of urea = 10 g Mass of water = 100 - 10 = 90 g Molar mass of urea ( NH _2 CONH _2) = 14 + 2 + 12 + 16 + 14 + 2 = 60 g mol^ -1 Molar mass of water ( H _2 O ) = 18 g mol^ -1 Moles of urea, n_ urea = 10 60 = 1 6 mol Moles of water, n_ water = 90 18 = 5 mol Total moles = 5 + 1 6 = 31 6 mol Mole fraction of water, x_ water = n_ water n_ water + n_ urea = 5 31 6 = 30 31 0.967 Answer: 0.967
Related: Chemistry — Solutions · All PYQ Banks