JEE Main 2021 · ChemistryMultiple choiceSingle correctMediumRecall

JEE Main 25 July 2021, Shift 1, Chemistry Q35

Question 35 of 90 in this shift, Chemistry question 5 of 30, Section A.

At 298.2 K the relationship between enthalpy of bond dissociation (in kJ mol

^{-1}

) for hydrogen (

\mathrm{E_H}

) and its isotope, deuterium (

\mathrm{E_D}

), is best described by :

(1) $\mathrm{E_H=E_D}$
(2) $\mathrm{E_H\simeq E_D-7.5}$ Official answer
(3) $\mathrm{E_H=2E_D}$
(4) $\mathrm{E_H=\frac{1}{2}E_D}$

Official answer

Option 2

NTA final key.

Chapter: Hydrogen
Topic: Hydrogen and Hydrides
Idea tested: H-H Bond Dissociation Enthalpy

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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.