Assertion `(A)`: The `IUPAC` name of isoprene is 2-methy1 buta-1,3-diene.
Reason `(R )`: Isoprene unit is a monomer of natural rubber

Options

A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation for `(A)`.
B. If both `(A)` and `(R )` are correct and `(R )` is not the correct explanation.
C. If `(A)` is correct and `(R )` is incorrect.
D. If both `(A)` and `(R )` are incorrect.

Explanation

To answer the question regarding the assertion and reason provided, we will evaluate both statements step by step.

### Step 1: Analyze the Assertion
- **Assertion (A)**: The IUPAC name of isoprene is 2-methylbuta-1,3-diene.

**Explanation**:
- Isoprene is a hydrocarbon with the molecular formula C5H8.
- Its structure can be represented as CH2=C(CH3)-CH=CH2.
- In this structure, we can see that there is a buta (four carbon) backbone with a methyl group (CH3) attached to the second carbon.
- The presence of double bonds at the first and third positions confirms the diene part of the name.
- Therefore, the correct IUPAC name for isoprene is indeed 2-methylbuta-1,3-diene.

### Step 2: Analyze the Reason
- **Reason (R)**: Isoprene unit is a monomer of natural rubber.

**Explanation**:
- Isoprene (C5H8) is the building block (monomer) of natural rubber.
- Natural rubber is a polymer made from the polymerization of isoprene units.
- This means that the statement is true as isoprene is essential for the formation of rubber.

### Step 3: Conclusion
- Both the assertion and the reason are true.
- The assertion is correct because the IUPAC name of isoprene is indeed 2-methylbuta-1,3-diene.
- The reason is also correct as isoprene is a monomer of natural rubber.

### Final Answer
Both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion.

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