Why is potassium dichromate a good oxidizing agent?

Hint: We need to know that the oxidizing agent is also known as oxidant. And the oxidizing agent is a species which has the ability to oxidize other substances. Which means, there is an increase in the oxidation state of the species by removing the electrons. Oxygen, hydrogen peroxide and halogens are the common oxidizing agents. Always the oxidizing agent will always try to exist in its highest oxidation state due to their strong tendency to accept the electron which undergoes the reduction.

Complete answer:
As we know that the potassium dichromate is a good oxidizing agent. Because, when elements undergo a chemical reaction, they become highly electronegative and an atom's oxidation decreases. Particularly in acidic medium, the potassium dichromate acts as a powerful oxidizing agent. Because, in the acidic medium the oxidation number of chromium will change by. And this compound is mainly used to oxidize the alcohol. By using potassium dichromate, the primary alcohol is converted into carboxylic acids or aldehydes at particular conditions.
If the substance has stronger electron affinity, it has the greater oxidizing power. Hence, the weakest oxidizing agent does not have a strong tendency to accept the electrons and it does not have strong electron affinity.

Note:
We have to remember that there are two types of reactions that take place in the reduction process which is oxidation and reduction. In the case of oxidation reaction, the electrons are removed from the substance. But in the case of the reduction process, the electrons are adding to a substance. In the oxidation process, the oxygen is gained by the substance, and in the reduction process, the oxygen is lost by the substance.