The boiling point of 0.2 mol kg^- solution of X in water is greater than equimolal solution of Y in water. Which one of 
the following statements is true in this case ?  

Expression of elevation in boiling point:

${\mathrm{\Delta T}}_{\mathrm{b}}={\mathrm{iK}}_{\mathrm{b}}\mathrm{m}$
Given that:

${\left({\mathrm{\Delta T}}_{\mathrm{b}}\right)}_{\mathrm{X}}>{\left({\mathrm{\Delta T}}_{\mathrm{b}}\right)}_{\mathrm{Y}}$

Kb is the constant and it is same because solvent is the same. Value of m is also same. Hence, the only change in $∆{\mathrm{T}}_{\mathrm{b}}$ value is due to the value of i (Van't Hoff factor).

${\mathrm{i}}_{\mathrm{X}}>{\mathrm{i}}_{\mathrm{Y}}$

This indicates that X undergoes dissociation in water.