Are you familiar with the mechanism by which chromic acid oxidises 2° alcohols to ketones and 1° alcohols to acids?
Could you draw, for example, the mechanism for oxidation of cyclohexanol to cyclohexanone?
The key part of your reaction is that you are introducing an extra oxygen onto the aromatic ring. Where does this oxygen come from?
Ketones there is simply loss of electrons (i.e. oxidation) it is helpful if you draw the mechanism to see.
carboxylic acids, there is addition of an extra oxygen as well as loss of electrons. Where does this
extra oxygen come from? is it from the chromic acid or another source? Again draw the mechanism for yourself.
Now see if you can apply similar principals of that mechanism to the formation of the quinone. If electrons are pulled out of the aromatic system during oxidation by the Cr6+
what would you expect to happen to the aromatic ring (*hint*, look at electrophillic aromatic substitution mechanisms)