1. Use isotonic condition

For isotonic solutions at the same temperature:

$\pi = i C R T$

So,

$i_1 C_1 = i_2 C_2$

Here:

• For glucose, it is a non-electrolyte, so $i=1$
• For $K_2SO_4$, let van't Hoff factor be $i$

Thus,

$i \times 0.004 = 1 \times 0.01$

$i = \frac{0.01}{0.004} = 2.5$

2. Relate van't Hoff factor to degree of dissociation

$K_2SO_4$ dissociates as:

$K_2SO_4 \rightarrow 2K^+ + SO_4^{2-}$

So, 1 formula unit gives 3 particles.

If degree of dissociation is $\alpha$, then

$i = 1 + (3-1)\alpha = 1 + 2\alpha$

Given $i=2.5$,

$2.5 = 1 + 2\alpha$

$2\alpha = 1.5$

$\alpha = 0.75$

3. Convert to percentage dissociation

$\%\text{ dissociation} = 0.75 \times 100 = 75\%$

4. Nearest integer

$\boxed{75}$