Question

The heat of combustion of `CH_(4(g)), C_((g))` and `H_(2(g))` at `25^(@)C` are `-212.4` K cal, -94.0 K cal and -68.4 K cal respectively, the heat of formation of `CH_(4)` will be -
A. `+54.4kcal`
B. `-18.4 kcal`
C. `-375.2 kcal`
D. `+212.8 kcal`

Answer 1

Correct Answer - B
`DeltaH_(f)(CH_(4))=(DeltaH_(comb)"of"C+2xxDeltaH_(comb)"of"H_(2)-DeltaH_(comb)"of"CH_(4))`