Q 1167367285.     A burner should have an optimum fuel to oxygen ratio in order to get maximum calorific output which corresponds to `3` times as much oxygen as is required theoretically for complete combustion of the fuel. A burner which has been adjusted for `CH_4` as fuel (`2` L/hour of `CH_4` and `12` L/hour of `O_2`) is to be readjusted for an equi-molar mixture of ethane and butane under the same condition of temperature and pressure. In order to get the same calorific output what should be the rate of supply of oxygen (in Litre/hr)? Assume the gases to behave ideally and losses due to incomplete combustion, etc., are the same for both the fuels.

Enthalpy of combustion: `CH_4= -810` kJ `mol^-1`;

`C_2H_6 = -1560` kJ; `C_4H_(10) = -2880` kJ `mol^-1`