1)

 The heats of combustion of carbon and carbon monoxide are - 393.5 and - 283.5 kJ mol-1, respectively. The heat of formation (in kI) of carbon monoxide per mole is


A) 676.5

B) -676.5

C) -110.5

D) 110.5

Answer:

Option C

Explanation:

$C(s)+O_{2}(g)\rightarrow CO_{2} g ;$

$\Delta H = -393.5 kJ$$ mol^{-1}$ .........(i)

$CO -O \rightarrow CO_{2} g$

$\Delta H = -283.5 kJ mol^{}$ .............(ii)

On subtracting Eq (i) and (ii)

$C(s)+\frac{1}{2} O_{2}(g)$;

$\Delta H =(-393.5+283.5)kJ $$mol^{-1 }= -110 kJ$$ mol^{-1}$