Question

How do you identify reducing agents, oxidizing agents, or whether neither of these two apply?

Answer 1

Those which give oxygen (or gain hydrogen) are called oxidising agent

Those which give hydrogen (or gain oxygen) are called reducing agent

For example CuO +H2 ---->CU +H2O

CuO is reduced to Cu..... hence CuO is oxidising agent

and....2 Cu + O2 ------> 2CuO

O2 is reduced to CuO. so.... O2 is oxidising agent