Question

The concentration in $\text{g/L}$ of a solution of cane sugar (Molecular weight $\text{=}\text{342)}$ which is isotonic with a solution containing $\text{6}\text{g}$ of urea $\text{(Molecular weight}\text{=}\text{60)}$ per litre is

• A. 3.42
• B. 34.2
• C. 5.7
• D. 19

Answer 1

Answer: (B)

The two solution should have same molar concentration for being isotonic.

Molar concentration of cabe sugar = Molar concentration of urea $=\frac{6}{60}=\text{0.1}\text{ mol/L}$

concentration of cane sugar in $\text{g/L}$

$\text{= molar concentration }\times \text{ molecular weight}$

$\text{=}\text{0}\text{.1}\times \text{342}\text{=}\text{34}\text{.2}$