What is the oxidation state of carbon in carbon dioxide?

Let $\mathrm{x}$ be the oxidation state of $C$ in ${\mathrm{CO}}_2$.

Since, the overall charge on the complex is 0 , the sum of oxidation states of all elements in it should be equal to 0 .

X+2(-2)=0

or, $\text{x=+4}$