Question

$3$ gms of urea is dissolved in $45$ gms of $H_{2}O$. The relative lowering in vapour pressure is :

• A. $0.05$
• B. $0.04$
• C. $0.02$
• D. $0.01$

Answer 1

The correct option is C $0.02$

Relative lowering of vapour pressure is given by:

$\frac{P^o-P}{P^o}=X_{solute}=\frac{n_2}{n_1}=\frac{\frac{3}{60}}{\frac{45}{18}}=0.02$