Identify the oxidizing agent and reducing agent

[Suy]

Homework Statement

Sn(s)+NO₃^--->SnO₂(s)+NO_(g)

Homework Equations

The Attempt at a Solution

0 |+5 ,-2| |+4,-2| |+2,-2|
Sn(s)+NO₃^--->SnO₂(s)+NO_(g)
Sn lost 4e reducing agent
N gain 3e oxidizing agent
is that right?
What about oxygen?? do i do the same thing?
thanks

 

[Firelion]

The Oxygen is neither gained nor lost electrons. It stays by -2.
and yes I thibk you`re right.