It is the reaction that converts a metal into its cation at anode .

Answer

To solve the question regarding the reaction that converts a metal into its cation at the anode, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The question states that a metal is being converted into its cation at the anode. This means that a neutral metal atom is losing electrons to form a positively charged ion (cation).

2. **Identifying the Metal and Cation**:
- Let's take an example of sodium (Na). In its neutral state, sodium has an oxidation state of 0. When it loses one electron, it becomes a sodium cation (Na⁺) with an oxidation state of +1.

3. **Defining Oxidation**:
- The process of losing electrons is known as oxidation. Therefore, when sodium loses an electron to become Na⁺, it undergoes oxidation.

4. **Role of the Anode**:
- In electrochemistry, the anode is the electrode where oxidation occurs. This means that at the anode, metals will lose electrons and be converted into cations.

5. **Conclusion**:
- Since the question specifically asks about the reaction that converts a metal into its cation at the anode, we conclude that this process is called oxidation.

### Final Answer:
The reaction that converts a metal into its cation at the anode is known as **oxidation**.

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