If the degree of association is $70 \%$ for the reaction $2 A \rightleftharpoons (A)_2$, the van't-Hoff factor for the solute $A$ is

$A$ $0.004 \ M$ solution of $Na_2SO_4$ is isotonic with a $0.010 \ M$ solution of glucose at the same temperature. The apparent degree of dissociation of $Na_2SO_4$ is $..... \ \%$.

$A$ non-volatile solute '$A$' tetramerizes in water to the extent of $80\%$. $2.5 \text{ g}$ of '$A$' in $100 \text{ g}$ of water lowers the freezing point by $0.3^\circ \text{C}$. The molar mass of $A$ in $\text{g mol}^{-1}$ is ($K_f$ for water $= 1.86 \text{ K kg mol}^{-1}$)

$A$ solute $A$ dimerizes in water. The boiling point of a $2 \, M$ solution of $A$ is $100.52^{\circ} C$. The percentage association of $A$ is ..... $\%$.
(Round off to the Nearest integer)
[Use : $K_{b}$ for water $= 0.52 \, K \, kg \, mol^{-1}$,Boiling point of water $= 100^{\circ} C$]

The Van't Hoff factor of $BaCl_2$ at a concentration of $0.01 \ M$ is $1.98$. The percentage dissociation of $BaCl_2$ at this concentration will be: (in $\%$)

$2 \,g$ of benzoic acid $(C_{6}H_{5}COOH)$ dissolved in $25 \,g$ of benzene shows a depression in freezing point equal to $1.62 \,K$. The molal depression constant for benzene is $4.9 \,K \,kg \,mol^{-1}$. What is the percentage association of the acid if it forms a dimer in the solution?