What is the chromatic number $\chi(Q_4)$ of a four-dimensional cube. I know that all Hypercubes $Q_d$ are bipartite, so then this would yield $\chi(Q_4) = 2$, because every bipartite graph has chromatic number $2$. Am I right, because the question then looks too simple? And this applies also for $Q_3$?
If not, then it would be $4$, because it is 4-regular graph. But that more or less applies for the chromatic index.
Yes, you're right: All hypercube graphs are bipartite, and "bipartite" means exactly "has chromatic number $\le 2$".