The enthalpy of formation of CO₂(g), H₂O(l) and propene (g) are -393.5, -285.8, and 20.42 kJ mol^-1 respectively. The enthalpy change for the combustion of cyclopropane at 298 K will be:

(The enthalpy of isomerization of cyclopropane to propene is -33.0 kJ mol^-1. )
1. -1021.32 kJ mol^-1
2. -2091.32 kJ mol^-1
3. -5021.32 kJ mol^-1
4. -3141.32 kJ mol^-1

The enthalpies of formation of Al₂O₃ and Cr₂O₃ are – 1596 kJ and – 1134 kJ, respectively. ∆H for the reaction 2Al + Cr₂O₃ → 2Cr + Al₂O₃ is -

4.8 g of C(diamond) on complete combustion evolves 1584 kJ of heat. The standard heat of the formation of gaseous carbon is 725 kJ/mol. The energy required for the given process will be:

(i) $\mathrm{C}\left(\mathrm{graphite}\right)\to \mathrm{C}\left(\mathrm{gas}\right)$

(ii) $\mathrm{C}\left(\mathrm{diamond}\right)\to \mathrm{C}\left(\mathrm{gas}\right)$