Question

12 g of urea is dissolved in 1 L of water and 68.4 g of sucrose is dissolved in 1 L of water. The lowering of vapour pressure of urea is

• A. equal to sucrose
• B. greater than sucrose
• C. less than sucrose
• D. double that of sucrose

Answer 1

Answer: (A)

equal to sucrose

Answer 2

$12\, g$ urea $= \frac{12}{60} = 0.2 \,mol,$ $68.4 \,g$ sucrose $=\frac{68.4}{342} = 0.2\,mol$ As mole fraction of solute is same hence, lowering of vapour pressure is same.