Question

A solution containing 8.6 g urea in one litre was found to be isotonic with a 5% (wt./vol.) solution of an organic non-volatile solute. The molecular weight of latter is :

• A. $348.9$
• B. $34.89$
• C. $3489$
• D. $861.2$

Answer 1

The correct option is A $348.9$

The molar mass of an organic non-volatile solute is 348.9 g.
For two non-electrolytic solutions, if isotonic $C_1=C_2$;
$\therefore \frac{8.6}{60\times 1}=\frac{5\times 1000}{m\times 100}$

$\therefore m=348.9$