The combustion equations of carbon and carbon monoxide are as follows: C + O2 = CO2, ΔH = – 394 kJ/kg .mole CO + ½ O2 = CO2, ΔH = – 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