Question

A solution containing $500g$ of a protein per litre is isotonic with a solution containing $3.42g$ of sucrose per litre. The molecular mass of protein is:

• A. $5$
• B. $146$
• C. $34200$
• D. $50000$

Answer 1

The correct option is D $50000$

Two solutions are said to isotonic when they are at the same concentrations.

The molar mass of sucrose $=342$

$C_1=$ Concentration of protein

$C_2=$ Concentration of sucrose

Since, they are isotonic, $C_1=C_2$

$\frac{500}{\text{Molar mass of protein}}=\frac{3.42}{342}$

$⟹$ Molar mass of protein $=500\times 100=50000$ $g$