JEE Main 2025 · ChemistryNumerical answerNumerical valueMediumMulti-step

JEE Main 2 April 2025, Shift 2, Chemistry Q73

Question 73 of 75 in this shift, Chemistry question 23 of 25, Section B.

When 1 g each of compounds AB and

\mathrm{AB_2}

are dissolved in 15 g of water separately, they increased the boiling point of water by 2.7 K and 1.5 K respectively. The atomic mass of A (in amu) is __________

\times10^{-1}

(Nearest integer) (Given : Molal boiling point elevation constant is

0.5\ \mathrm{K\ kg\ mol^{-1}}

)

Official answer

NTA final key.

Chapter: Solutions
Topic: Colligative Properties
Idea tested: Boiling Point Elevation

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Asked 5× in all

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.