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
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
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