What do primary and secondary alcohols do to the color of Cr2O7 2- in a chemical reaction?

Primary and secondary alcohols are oxidized by dichromate ions, represented as Cr2O7^2-. During this oxidation process, the chromium in the dichromate ions is reduced from a +6 oxidation state to a +3 oxidation state.

When the dichromate solution, which has an orange color due to the Cr2O7^2- ions, reacts with primary or secondary alcohols, the solution changes color. The reduction of the chromium results in the formation of Cr^3+ ions, which impart a green color to the solution. Therefore, the visual change from the initial orange of dichromate to green indicates that a reaction has taken place, effectively showcasing the oxidative capability of primary and secondary alcohols in the presence of dichromate.

The other options involve colors that are either not correct for the oxidation of these alcohols with dichromate or represent different chemical reactions not relevant to this specific context.