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At 25°C and 1 atm pressure, the enthalpies of combustion are as given below : Substance H 2 C(graphite) C 2 H 6 (g) c 1 D H kJmol Θ − –286.0 –394.0 –1560.0 The enthalpy of formation of ethane is

1. +54.0 kJ mol –1
2. –68.0 kJ mol –1
3. –86.0 kJ mol –1
4. +97.0 kJ mol –1

Correct answer: –86.0 kJ mol –1

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