If at 298 K the bond energies of $C-H$, $C-C$, $C=C$ and $H-H$ bonds are respectively $414, \; 347, \; 615$ and $435 \; k \; J \; mol^{-1}$, the value of enthalpy change for the reaction <br> $H_2C = CH_2(g) + H_2(g) \to H_3C - CH_3 (g)$ at 298 K will be :
