(A): `Ce^(4+)` is a good oxidizing agent.
(R): `Sm^(2+)` is a good reducing agent. 

Options

A. Both A & R are true, R is the correct explanation of A
B. Both A & R are true, R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true

Answer

To solve the assertion-reason question regarding the properties of `Ce^(4+)` and `Sm^(2+)`, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
**Assertion (A):** `Ce^(4+)` is a good oxidizing agent.

- **Explanation:** Cerium (Ce) belongs to the lanthanide series and has an atomic number of 58. In its +4 oxidation state, it has the electronic configuration of [Xe] 4f^1 5d^1 6s^2. The +4 state is higher in energy compared to the +3 state, which is the most stable and common oxidation state for lanthanides. A good oxidizing agent is characterized by its ability to accept electrons. Since `Ce^(4+)` can readily accept an electron to revert to the more stable `Ce^(3+)`, it acts as a good oxidizing agent.

### Step 2: Analyze the Reason
**Reason (R):** `Sm^(2+)` is a good reducing agent.

- **Explanation:** Samarium (Sm) has an atomic number of 62. In its +2 oxidation state, it has the electronic configuration of [Xe] 4f^6 6s^2. The +3 oxidation state is the most stable for samarium as well. A good reducing agent is characterized by its ability to donate electrons. Since `Sm^(2+)` can lose an electron to become `Sm^(3+)`, it acts as a good reducing agent.

### Step 3: Determine the Relationship
- Both statements are true:
- `Ce^(4+)` is indeed a good oxidizing agent because it can accept an electron to become `Ce^(3+)`.
- `Sm^(2+)` is a good reducing agent because it can donate an electron to become `Sm^(3+)`.
- However, the reason provided does not explain the assertion directly. The assertion and reason are related to their respective oxidation states but do not have a direct cause-and-effect relationship.

### Conclusion
- **Final Answer:** Both assertion and reason are true, but the reason is not the correct explanation of the assertion. Therefore, the correct option is that both statements are true, but the reason does not explain the assertion.

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