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