For an aqueous solution of $FeSO_4$, the experimental molecular mass is found to be $80 \ g/mol$. What is the degree of dissociation of the salt?

Solute $A$ associates in water. When $0.7 \ g$ of solute $A$ is dissolved in $42.0 \ g$ of water,it depresses the freezing point by $0.2^{\circ} C$. The percentage association of solute $A$ in water is $..... \ \%$.
[Given: Molar mass of $A = 93 \ g \ mol^{-1}$. Molal depression constant of water is $1.86 \ K \ kg \ mol^{-1}$]

If $\alpha$ is the degree of dissociation of $Na_2SO_4$,the Van't Hoff factor $(i)$ used for calculating the molecular mass is

Benzoic acid molecules undergo dimerisation in benzene. $2.44 \ g$ of benzoic acid when dissolved in $30 \ g$ of benzene caused a depression in freezing point of $2 \ K$. What is the percentage of association of it? (Given $K_f(C_6H_6) = 5 \ K \ kg \ mol^{-1}$; molar mass of benzoic acid $= 122 \ g \ mol^{-1}$)

Explain abnormal molar masses.

In an experiment to estimate the molecular weight of benzoic acid by the elevation in boiling point method, the experimental value of the molecular weight was double the actual value. Calculate the degree of association of the dimer.