28.0 L of CO$$_2$$ is produced on complete combustion of 16.8 L gaseous mixture of ethene and methane at 25°C and 1 atm. Heat evolved during the combustion process is _____ kJ
Given: $$\Delta H_C$$(CH$$_4$$) = -900 kJ mol$$^{-1}$$
$$\Delta H_C$$(C$$_2$$H$$_4$$) = -1400 kJ mol$$^{-1}$$.