Which of the following has the same van't Hoff factor $(i)$ as $K_3[Fe(CN)_6]$?

The van't Hoff factor $(i)$ for a dilute aqueous solution of the strong electrolyte barium hydroxide is

If $1$ mole of a solute dissociates to give $n$ number of ions,then the degree of dissociation $\alpha$ in terms of the van't Hoff factor $i$ is given by:

In an aqueous solution of $NaCl$,the mole fraction of the solvent is $0.9$. Then,the relative lowering in vapour pressure will be ......... $atm$.

Which of the following solutions in water possesses the lowest vapour pressure?

If $0.004 \ M \ Na_2SO_4$ and $0.01 \ M$ glucose aqueous solutions are isotonic,then the degree of dissociation of $Na_2SO_4$ is ........ $\%$.