Which of the following is an oxidation reaction?

A.
AuCl4- → AuCl 2- ****

B.
Mn7+ → Mn2+

C.
Cl2 → ClO3-

D.
Co3+ → Co2+

2 answers

c. Cl in Cl2 lost electrons to to a positive state (Cl+5)
Darn that was my first answer, I just second guessed myself...thank you!