Question

A solution is obtained by dissolving 12g of urea (Mol.wt.=60) in a litre of solution. Another solution is prepared by dissolving 68.4g of cane sugar(Mol.wt.=342) in a litre of solution at the same temperature. The lowering of vapour pressure in the first solution is:

• A. nearly 5 times that of the second solution
• B. same as that of second solution
• C. double that of second solution
• D. nearly one fifth of the second solution

Answer 1

The correct option is B same as that of second solution

For urea $\Delta P_1=X_{urea}{P}^0$

$\Delta P_1=\frac{\frac{12}{60}}{totalmole}{P}^0$

$\Delta P_1=\frac{0\cdot 2}{totalmole}{P}^0$ ----(1)

For sugar $\Delta P_2=X_{sugar}{P}^0$

$\Delta P_2=\frac{\frac{68\cdot 4}{342}}{totalmole}{P}^0$

$\Delta P_2=\frac{0\cdot 2}{totalmole}{P}^0$ ----(2)

Hence $\left(1\right)=\left(2\right)$

Hence, the correct option is $B$