# What is a "subvalent oxide"? Can you give an example?

A suboxide of carbon found in flames is carbon suboxide, ${C}_{3} {O}_{2}$, where the carbon oxidation states are $O = \stackrel{+ I I}{C} = \stackrel{0}{C} = C = O$, where the average carbon oxidation number is $+ \frac{4}{3}$, but the individual oxidation states are clearly $\stackrel{0}{C}$, and $\stackrel{+ I I}{C}$. An even better example of a subvalent oxide is carbon monoxide itself, which features a formal $C \left(+ I I\right)$ carbon oxidation state.
On the other hand, for non-suboxide carbon oxides, $C {O}_{2}$ and $C B {r}_{4}$, each carbon has the same oxidation state, which are?