Question

$5\%$ solution of sucrose is isotonic with $1\%$ solution of a compound $A$ then the molecular weight of compound $A$ is :

• A. $32.4$
• B. $68.4$
• C. $121.6$
• D. $34.2$

Answer 1

The correct option is B $68.4$

Molar conc. of cane sugar solution:

$=\frac{5}{342}\times \frac{1000}{100}=\frac{50}{342}$

Molar conc. of solution $X=\frac{l}{m}\times \frac{1000}{100}$

$=\frac{10}{m}$

$\frac{10}{m}=\frac{50}{342}$ or

$m=68.4$