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)

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