Question

Solute A is a ternary electrolyte and solute B is a non-electrolyte. If 0.1 M solution of solute B produces an osmotic pressure of 2P, then 0.05 M solution of A at the same temperature will produce an osmotic pressure equal to:

• A. 1.5P
• B. 2P
• C. 3P
• D. P

Answer 1

Answer: (C)

3P

Ternary electrolyte implies the van't Hoff factor is 3.

Now, Osmotic pressure, $\pi =CRT\times i$

Solute A is ternary,

$i=3$

$C=0.05M$

Solute B is a non-electrolyte,

$i=1$

$C=0.1M$

$\pi =2P$

At same temperature,

$\therefore ,\frac{{\pi }_1}{C_1{i}_1}=\frac{{\pi }_2}{C_2{i}_2}$

$\Rightarrow \frac{2P}{0.1}=\frac{{\pi }_2}{0.05\times 3}$

$\Rightarrow {\pi }_2=3P$

Hence, the correct option is $C$.