The combustion equations of carbon and carbon monoxide are as follows: C + O2 = CO2, ΔH = - 394 kJ/kg . mole CO + 1/2 O2 = CO2, ΔH = - 284.5 kJ/kg. mole. The heat of formation of CO is __________ kJ/kg. mole.

• -109.5
• +109.5
• +180
• +100