Question

I need to identify the elements oxidized and reduced and indicate which
substances are the oxidizing and reducing agents for the redox reaction:
PH3(g) + O2(g) → P2O5(s) + H2O(g)

Answer 1

P goes from+3 to +5: it lost electrons, and therefor is oxidized.
O2 goes from zero to -2, it gained electrons, and therefore is reduced.

P is the reducing agent, O is the oxidizing agent.

Answer 2

Awesome! Thanks:)