Verified answer

Heat of reaction.....

CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l)...................... ΔHrx = ???

You may be having trouble because there is a typo in your table. The heat of formation of CO2 is −393.5kJ/mol.

Find the heat of combustion of methane from heats of formation.

ΔHrx = ΣΔHf(products) - ΣΔHf(reactants) ..................................... Σ = "sum of"

ΔHrx = (-393.5 kJ + 2(-285.8 kJ)) - (-74.9 kJ)

ΔHrx = -890.2 kJ

Heats of formation table: https://en.wikipedia.org/wiki/Standard_enthalpy_of...