_____________ the chemical change that occurs at this electrode is called _____________.

Options

A. anode, oxidation
B. anode, reduction
C. cathode, oxidation
D. cathode, reduction

Explanation

**Step-by-Step Solution:**

1. **Identify the Electrodes**: In electrolysis, there are two electrodes: the anode and the cathode. The anode is connected to the positive terminal of the battery, while the cathode is connected to the negative terminal.

2. **Understand the Processes at Each Electrode**:
- At the anode, oxidation occurs. This means that a substance loses electrons.
- At the cathode, reduction occurs. This means that a substance gains electrons.

3. **Apply the Concepts to a Specific Example**:
- Consider the electrolysis of molten sodium chloride (NaCl). When NaCl is electrolyzed, it dissociates into Na⁺ and Cl⁻ ions.
- The Na⁺ ions migrate towards the cathode (negative electrode), while the Cl⁻ ions migrate towards the anode (positive electrode).

4. **Determine the Reactions at Each Electrode**:
- At the anode, Cl⁻ ions undergo oxidation. They lose electrons to form Cl₂ gas.
- At the cathode, Na⁺ ions undergo reduction. They gain electrons to form sodium metal.

5. **Conclude the Chemical Changes**:
- The chemical change that occurs at the anode is called oxidation.
- The chemical change that occurs at the cathode is called reduction.

**Final Answer**: The chemical change that occurs at this electrode is called oxidation (at the anode) and reduction (at the cathode).

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