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 methan=16
Heat produced per gram of methane`=-(890.3)/(16)=-55.63kJ`
Molar mass of methane =58
Heat produced per gram of butane `=-(2878.7)/(58)=-49.63kJ`
thus, methane has greater fuel efficiency than butane.