$A$ $0.1 \ mol$ of a binary electrolyte undergoes complete dissociation in $250 \ g$ of a protic solvent. If the elevation in boiling point is $1.5 \ K$,the molal elevation constant $(K_b)$ is ............. $K \ kg \ mol^{-1}$.

Consider the following solutions:
$I$. $1 \ M$ glucose $(aq.)$
$II$. $1 \ M$ sodium chloride $(aq.)$
$III$. $1 \ M$ acetic acid in benzene
$IV$. $1 \ M$ ammonium phosphate $(aq.)$

When $0.01 \ mol$ of sodium sulphate $(Na_2SO_4)$ is dissolved in $1 \ kg$ of water,complete ionization of the solution is observed. Calculate the decrease in the freezing point of the solution. $(K_f = 1.86 \ K \ kg \ mol^{-1})$

At higher altitude,the boiling point of water is $95\,^oC$. The amount of $NaCl$ added to $1\,kg$ of water $(K_b = 0.52\,K\,kg\,mol^{-1})$ in order to raise the boiling point of the solution to $100\,^oC$ (assume $90\%$ ionisation of $NaCl$) is .......... $g$.

For $0.1 \ M$ solutions of the following electrolytes,the colligative property will follow the order:

The van't Hoff factor for $Ca(NO_3)_2$ is ...... .