`C_("graphite")+O_(2)(g)rarrCO_(2)(g)`
`deltaH=-94.05Kcalmol^(-1)`
`C_("diamond")+O_(2)(g),DeltaH=-94.50Kcalmol^(-1)
Therefore,

Options

A. `C_(("graphite")) rarr C_(("diamond")) , Delta H_(298K)^(@)= - 450cal mol^(-1)`
B. `C_(("diamond")) rarr C_(("graphite")), Delta H_(298K)^(@) = +450 cal mol^(-1)`
C. Graphite is the stabler allotrope
D. Diamond is harder than graphite

Answer

C

Explanation

C(graphite) `+ O_(2)(g) rarr CO_(2)(g), Delta H = -94.05` kcal/mole
C(diamond) `+O_(2)(g) rarr CO_(2)(g), Delta H= -94.50` kcal/mole
C(graphite) `rarr C` (diamond), `Delta H= -94.05+ 94.50 = +450` cal/mol
So graphite is the stabler allotrope. Hardness of two compounds cannot be predicted from the given equations