Question

A solution containing 8.6 g urea in 1 L was found to be isotonic with a 5% (weight/volume) solution of an organic non-volatile solute. The molecular weight in $g/mol$ of later is:

• A. 348.83
• B. 34.89
• C. 3489
• D. 861.2

Answer 1

Answer: (A)

348.83

For two non-electrolyte solutions, if isotonic $C_1=C_2$.

$\therefore \frac{8.6}{60\times 1}=\frac{5\times 1000}{M{w}_2\times 100}$

$\Rightarrow M{w}_2=348.83$

Hence, option A is correct.