Mg (s) + Cu (NO3) 2 (aq) → Mg (NO3) 2 (aq) + Cu (s)

what is the oxidizing agent and the reducing agent

1. The reaction is:

Mg (s) + Cu (NO3) 2 (aq) → Mg (NO3) 2 (aq) + Cu (s)

The oxidizing agent is the one that is being reduced which is copper where the charge changed from + 2 to neutral while the reducing agent is the on being oxidized which is magnesium where the charge change from neutral to + 2.