For a dilute solution of $K_3[Fe(CN)_6]$,the van't Hoff factor $(i)$ is ..... [assuming $100\%$ ionization]

Which one of the following is the ratio of the lowering of vapour pressure of $0.1 \ M$ aqueous solutions of $BaCl_2, NaCl$ and $Al_2(SO_4)_3$ respectively?

$A$ solution of $17.1$ $w\%$ of sucrose (molar mass $= 342 \ g \ mol^{-1}$) is isotonic with a $x$ $w\%$ solution of oxalic acid (molar mass $= 90 \ g \ mol^{-1}$). Assume the degree of dissociation of oxalic acid as $0.01$. What is $x$?

Which of the following has the lowest freezing point?

Which of the following aqueous solutions has the highest freezing point?

$17.4\% \text{ (mass/volume) } K_2SO_4$ solution at $27^\circ C$ is isotonic to $5.85\% \text{ (mass/volume) } NaCl$ solution at $27^\circ C$. If $NaCl$ is $100\%$ ionized,what is the $\%$ ionization of $K_2SO_4$ in aqueous solution? [Atomic weights: $K = 39, Na = 23, S = 32, O = 16, Cl = 35.5$]