$1.24 \ g$ of $AX_2$ (molar mass $124 \ g \ mol^{-1}$) is dissolved in $1 \ kg$ of water to form a solution with a boiling point of $100.0156^{\circ} C$,while $25.4 \ g$ of $AY_2$ (molar mass $250 \ g \ mol^{-1}$) in $2 \ kg$ of water constitutes a solution with a boiling point of $100.0260^{\circ} C$. $K_{b}(H_2O) = 0.52 \ K \ kg \ mol^{-1}$. Which of the following is correct?

• A
  $AX_2$ and $AY_2$ (both) are completely unionised.
• B
  $AX_2$ and $AY_2$ (both) are fully ionised.
• C
  $AX_2$ is completely unionised while $AY_2$ is fully ionised.
• D
  $AX_2$ is fully ionised while $AY_2$ is completely unionised.