$0.004 \ M \ Na_2SO_4$ is isotonic with $0.01 \ M$ glucose. The degree of dissociation of $Na_2SO_4$ is ........... $\%$.

$20 \ g$ of naphthoic acid $(C_{11}H_8O_2)$ dissolved in $50 \ g$ of benzene $(K_f = 1.72 \ K \ kg \ mol^{-1})$ shows a depression in freezing point of $2 \ K$. The Van't Hoff factor is?

$1.2 \, mL$ of acetic acid is dissolved in water to make $2.0 \, L$ of solution. The depression in freezing point observed for this strength of acid is $0.0198^{\circ} C$. The percentage of dissociation of the acid is $....$ (Nearest integer)
[Given : Density of acetic acid is $1.02 \, g \, mL^{-1}$
Molar mass of acetic acid is $60 \, g \, mol^{-1}$
$K_{f}(H_{2}O) = 1.85 \, K \, kg \, mol^{-1}$]

$A$ solute $A$ undergoes association in a medium as $nA \rightleftharpoons A_n$. If the degree of association is $\alpha$,then the van't Hoff factor $i$ is given by:

$1.2 \ mL$ of acetic acid having density $1.06 \ g \ cm^{-3}$ is dissolved in $1 \ L$ of water. The depression in freezing point observed for this concentration of acid was $0.041^{\circ} C$. The van't Hoff factor of the acid is $(K_f \text{ of water } = 1.86 \ K \ kg \ mol^{-1})$

One mole of a solute $A$ is dissolved in a given volume of a solvent. The association of the solute takes place according to $nA \rightleftharpoons (A)_n$. The Van't Hoff factor $i$ is expressed as: