For the dissociation of $Na_2SO_4$,how is the degree of dissociation $\alpha$ used to calculate the van't Hoff factor $(i)$?

$0.004 \ M$ $Na_2SO_4$ solution is isotonic with $0.01 \ M$ glucose solution,then the degree of dissociation of $Na_2SO_4$ is ........... $\%$.

If the degree of ionisation of $KI_3$ is $80\%$,then what will be its van't Hoff factor?

Which of the following salts has the same value of Van't Hoff factor $i$ as that of $K_4[Fe(CN)_6]$?

What is the percentage of dissociation of a $0.011 \ m$ aqueous solution of $K_3[Fe(CN)_6]$ having a freezing point of $-0.063 \ ^oC$? (Given: $K_f = 1.86 \ K \ kg \ mol^{-1}$ for water)

$17.4\% \ (W/V)$ solution of potassium sulphate (mol. $wt. = 174$) is isotonic with $4\% \ (W/V)$ aqueous solution of $NaOH$. If $NaOH$ is $100\%$ ionised,the degree of ionisation of potassium sulphate is $........... \ \%$.