ΔH= dissociation energy of reactant - Bond dissociation of energy of product. ΔH=(606.10+4×410.5+431.37)−(6×410.50+336.49)=−120.0 kJ/mol
From the following bond energies : H- H bond energy : 431.37 ~kJ ~mol^-1 C= C bond energy : 606.10 ~kJ ~mol^-1 C- C bond energy : 336.49 ~kJ ~mol^-1…
NEET UG 2009 — Chemistry Physical Chemistry
2009mcqhard
From the following bond energies : H−H bond energy : 431.37 kJ mol−1 C=C bond energy : 606.10 kJ mol−1 C−C bond energy : 336.49 kJ mol−1 C−H bond energy : 410.50 kJ mol−1 Enthalpy for the reaction, 
will be :
Official previous-year question
Held on 30 Apr 2009 · Verified 9 Jul 2026.
Options
- A
553.0 kJ mol−1
- B
1523.6 kJ mol−1
- C
−243.6 kJ mol−1
- D
−120.0 kJ mol−1
Did you get this right?
Sign in to track your attempts and accuracy.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.
NEET UG Physical Chemistry in other years
More NEET UG Physical Chemistry questions
The unit of rate constant for a first-order reaction is:
2026easy
For the reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), ΔH = -198 kJ. Which condition favours forward reaction?
2026medium
$\begin{aligned} &\text { Consider the following compounds: }\\ &\mathrm{\underline{K}O}_2, \mathrm{H}_2 \mathrm{\underline{O}}_2 \text { and } \mathrm{H}_2 \mathrm{\underline{S}O}_4 \text {. } \end{aligned}$ The oxidation states of the underlined elements in them are, respectively,
2025easy
5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is true regarding the described solution?
2025medium
For the reaction $\mathrm{A}(\mathrm{g}) \rightleftharpoons 2 \mathrm{~B}(\mathrm{~g})$, the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500 , at 1000 K . [Given : $\mathrm{R}=0.0831 \mathrm{~L} \mathrm{~atm} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ ] $\mathrm{K}_{\mathrm{p}}$ for the reaction at 1000 K is
2025medium
Other Chemistry topics for NEET UG
Keep practicing Physical Chemistry
Work through every NEET UG Physical Chemistry PYQ, year by year.