Calculate the standard enthalpy of formation of acetylene from the following data `:`
`C_((g))+O_(2(g))rarr CO_(2(g)),DeltaH^(@)=-393kJ mol^(-1)`
`H_(2(g))+(1)/(2)O_(2(g)) rarr H_(2)O_((l)),DeltaH^(@)=-285.8kJ mol^(-1)`
`2C_(2)H_(2(g))+5O_(2(g))rarr 4CO_(2(g))+2H_(2)O_((l)),DeltaH^(@)=-2598.8kJ mol^(-1)`.