Final answer:
Copper (Cu) is the element that is oxidized in the reaction between copper and nitric acid, transforming from solid copper to its ionized form and losing electrons in the process.
Step-by-step explanation:
In the chemical reaction between copper (Cu) and nitric acid (HNO3), the element that is oxidized is copper (Cu). During the oxidation process, copper starts as a solid (Cu(s)) and is transformed into its ionized form Cu²⁺ (aq), losing two electrons in the process. The half-reaction for the oxidation of copper can be represented as follows:
Cu(s) → Cu²⁺ (aq) + 2e¯
This change in the electron count is what defines oxidation. Therefore, the correct answer to the student's question is A) Copper (Cu).
The nitric acid acts as an oxidizing agent and gets reduced in this reaction, but it is not itself oxidized. The nitrogen within the nitric acid undergoes a change from the +5 oxidation state in nitrate (NO3) to a lower oxidation state in nitric oxide (NO(g)).