Which of the following $0.05 \ M$ aqueous solution will have the lowest freezing point?

The Van't Hoff factor of the compound $K_3[Fe(CN)_6]$ is

When $10^{-3} \ M$ solution of glucose in water freezes at $-0.0186^{\circ} C$,then at what temperature $10^{-3} \ M$ solution of $NaCl$ will freeze (in $^{\circ} C$)?

We have three aqueous solutions of $NaCl$ labelled as $A$,$B$ and $C$ with concentrations $0.1 \ M$,$0.01 \ M$ and $0.001 \ M$,respectively. The value of van 't Hoff factor $(i)$ for these solutions will be in the order:

The observed osmotic pressure for a $0.10 \ M$ solution of $Fe(NH_4)_2(SO_4)_2$ at $25 \ ^oC$ is $10.8 \ atm$. The expected and experimental (observed) values of van't Hoff factor $(i)$ will be respectively: $(R = 0.082 \ L \ atm \ K^{-1} \ mol^{-1})$

The freezing point of a solution prepared by adding $8.1 \ g$ of $HBr$ ($90\%$ ionized) to $100 \ g$ of water is $...... \ ^\circ C$. (Given $K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$)