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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyRecall

JEE Main 4 August 2021, Shift 1, Chemistry Q37

Question 37 of 90 in this shift, Chemistry question 7 of 30, Section A.

Naturally occurring hydrogen contains three isotopes, protium (H), deuterium (D) and tritium (T). What is correct order of heat of dissociation for H2\mathrm{H_2}, D2\mathrm{D_2} and T2\mathrm{T_2} ?
  1. (1)H2>D2>T2\mathrm{H_2 > D_2 > T_2}
  2. (2)T2>D2>H2\mathrm{T_2 > D_2 > H_2}Official answer
  3. (3)H2=D2=T2\mathrm{H_2 = D_2 = T_2}
  4. (4)D2>T2>H2\mathrm{D_2 > T_2 > H_2}

Official answer

Option 2

NTA final key.

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

Same idea in other shifts

Asked 3× in all
  1. 31 Aug 2021, Shift 2 · Q34Which one of the following statements is incorrect ?MediumSingle correct
  2. 25 Jul 2021, Shift 1 · Q35At 298.2 K the relationship between enthalpy of bond dissociation (in kJ mol−1^{-1}) for hydrogen (EH\mathrm{E_H}) and its isotope,…MediumSingle correct

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 108 of the 174 JEE Main shifts held from 2017 to 2026.