The enthalpies of combustion of carbon and carbon monoxide are $390KJmo{l}^{-1}$ and $278KJmo{l}^{-1}$ respectively. The enthalpy of formation of carbon monoxide is

Given data: The enthalpies of combustion of carbon and carbon monoxide are $390KJmo{l}^{-1}$ and $278KJmo{l}^{-1}$ respectively.

Formula/Concept used: Hess’s law

Detailed solution: The reactions are given below:

$$\begin{gathered} C+O_2\to C{O}_2;\Delta \text{H = -390 KJ}..........\text{(i)} \\ \text{CO+}\frac{1}{2}{O}_2\to C{O}_2;\Delta \text{H = -278 KJ}..........\text{(ii)} \end{gathered}$$

The required reaction is:

$C+\frac{1}{2}{O}_2\to CO$ 

The required reaction be formed by subtracting equation (ii) from (i).

The enthalpy of the reaction is:

$$\begin{gathered} \Delta H\text{ = -390 - (-278)} \\ \Delta H\text{ = -112 KJ} \end{gathered}$$

Therefore, the correct option is C.