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JEE Main 4 April 2024, Shift 1, Chemistry Q83

Question 83 of 90 in this shift, Chemistry question 23 of 30, Section B.

The enthalpy of formation of ethane (

\mathrm{C_2H_6}

) from ethylene by addition of hydrogen where the bond-energies of C

-

H, C

-

C, C

=

C, H

-

H are 414 kJ, 347 kJ, 615 kJ and 435 kJ respectively is

-

________ kJ

Official answer

125

NTA final key.

Chapter: Thermodynamics (Chemistry)
Topic: Enthalpy and Hess's Law
Idea tested: Bond Enthalpy Calculations

Same idea in other shifts

Asked 5× in all

3 Apr 2025, Shift 1 · Q71Given : $\Delta H^{\ominus}_{sub}$ [C (graphite)] = 710 kJ mol $^{-1}$ $\Delta_{C-H}H^{\ominus}$ = 414 kJ mol $^{-1}$ …MediumNumerical value
13 Apr 2023, Shift 1 · Q83 $\mathrm{A_2}+\mathrm{B_2}\rightarrow 2\mathrm{AB}$ . $\Delta H_f^0 = -200\ \mathrm{kJ\ mol^{-1}}$ AB, $\mathrm{A_2}$ and $\mathrm{B_2}$ …MediumNumerical value
26 Feb 2021, Shift 2 · Q54The average S $-$ F bond energy in kJ $\mathrm{mol^{-1}}$ of $\mathrm{SF_6}$ is __________. (Rounded off to the nearest integer) [Given :…MediumNumerical value
18 Mar 2021, Shift 1 · Q53For the reaction $\mathrm{C_2H_6 \rightarrow C_2H_4 + H_2}$ the reaction enthalpy $\Delta_rH =$ __________ kJ mol $^{-1}$ . (Round off to…EasyNumerical value

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.