JEE Main 2021ChemistryThermodynamics (C)MediumNumerical

JEE Main 2021 — Thermodynamics (C) Question with Solution

JEE Main 2021 (18 Mar Shift 1)

Question

For the reaction
C2H6→C2H4+H2
the reaction enthalpy ∆rH in kJmol-1 is 
(Round off to the Nearest Integer).
[Given : Bond enthalpies in kJmol-1:C-C:
347,C=C:611;C-H:414,H-H:436]

Enter your answer

Show full solutionCorrect answer: 128
Correct answer
128

Step-by-step explanation

ΔrH=ϵC-C+2ϵC-H-ϵC=C+ϵH-H
=[347+2×414]-[611+436]
=128

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About this question

This is a previous-year question from JEE Main 2021, covering the Thermodynamics (C) chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.