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

• A. -109.5
• B. +109.5
• C. +180
• D. +100