The heats of combustion of `Ch_(4)` and `C_(4)H_(10)` are `-890.3` and `-2878.7 kJ mol^(-1)`, respectively. Which of the two has greater efficiency as fuel per gram?

Explanation

Molar mass of methane `= 16`
Heat produced per gram of methane `=- (890.3)/(16) =- 55.64 kJ`
Molar mass of butane `= 58`
Heat produced per gram of butane `=- (2878.7)/(58) =- 49.63 kJ`
Thus, methane has greater fuel efficiency than butane.