Chemistry-Enthalpy

NEET Chemistry Enthalpy MCQ Question

Type: MCQ-numerical-Hard-Class 11

Calculate the enthalpy change (ΔrH) for the reaction CH4(g) → C(g) + 4H(g) using the given bond enthalpy values: CH4(g) → CH3(g) + H(g); ΔbondH = +427 kJ/mol, CH3(g) → CH2(g) + H(g); ΔbondH = +439 kJ/mol, CH2(g) → CH(g) + H(g); ΔbondH = +452 kJ/mol, CH(g) → C(g) + H(g); ΔbondH = +347 kJ/mol.

A

+1665 kJ/mol

B

-1665 kJ/mol

C

+500 kJ/mol

D

-500 kJ/mol

Correct Answer

Option A

Detailed Explanation

The total enthalpy change for breaking all C-H bonds in CH4 is calculated by summing the bond enthalpies: +427 + 439 + 452 + 347 = +1665 kJ/mol.

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