∆ H_f^{\circ} for diamond.
∆ H_f^{\circ} values of graphite, diamond and {\C}_{60} are 0,1.9 and. 38.1 {\kJ} {\mol}^{-1} and ∆ H_f^{\circ} values are in order.
Fullerene > Diamond > Graphite." >
Graphite is the most stable state of carbon and its ∆Hf∘ is considered as zero. ( ∵ has more van der Waals' force) also ∆Hf∘ for C60>∆Hf∘ for diamond. ∆Hf∘ values of graphite, diamond and C60 are 0,1.9 and. 38.1kJmol−1 and ∆Hf∘ values are in order. Fullerene > Diamond > Graphite.
