1.24 g of AX₂ (molar mass 124 g mol ⁻¹) is dissolved in 1 kg of water to form a solution with boiling point of 100.0156° C, while 25.4 g of AY₂ (molar mass 250 g mol ⁻¹) in 2 kg of water constitutes a solution with a boiling point of 100.0260° C. K b (H₂O) = 0.52 K kg mol ⁻¹. Which of the following is correct ?

(D) AX₂ is fully ionised while AY₂ is completely unionised.

(A) AX₂ is completely unionised while AY₂ is fully ionised.

(B) AX₂ and AY₂ (both) are completely unionised.

(C) AX₂ and AY₂ (both) are fully ionised.

Solutions: JEE Main 2025 Chemistry question

JEE Main 2025 · 29 Jan, Morning shift · Q65

JEE Main 202529 Jan, Morning shiftChemistryMediumSolutions71× since 2002

1.24 g of

\mathrm{AX_2}

(molar mass 124 g mol

^{-1}

) is dissolved in 1 kg of water to form a solution with boiling point of 100.0156

^\circ

C, while 25.4 g of

\mathrm{AY_2}

(molar mass 250 g mol

^{-1}

) in 2 kg of water constitutes a solution with a boiling point of 100.0260

^\circ

K_b(\mathrm{H_2O}) = 0.52

K kg mol

^{-1}

. Which of the following is correct ?