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At 25ºC and 1 atm pressure, the enthalpy of combustion of benzene (I) and acetylene (g) are –3268 kJ mol –1 and –1300 kJ mol –1 , respectively. The change in enthalpy of the reaction 3C 2 H 2 (g) → C 6 H 6 (I), is

1. +324 kJ mol –1
2. +632 kJ mol –1
3. –632 kJ mol –1
4. –732 kJ mol –1

Correct answer: –632 kJ mol –1

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