PPA - Oxidation

What were the three oxidising agents used in this PPA?

Why can mild oxidising agents be used to distinguish between aldehydes and keytones?

Why were the reaction mixtures not heated directly using a bunsen burner?

With a successful reaction, what colour change is seen using acidified potassium dichromate?

With a successful reaction, what colour change is seen using benedicts solution?

With a successful reaction, what colour change is seen using tollens reagent?