Assertion : Addition of bromine to trans-but-2-ene yields meso-2,3-dibromobutane. ​
Reason : Bromine addition to an alkene is a nucleophilic addition
(a) If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.
(b) If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.
(c) I Assertion is CORRECT but Reason is INCORRECT.
(d)I Assertion is CORRECT but Reason is INCORRECT.

Options

A. If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.
B. If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.
C. I Assertion is CORRECT but Reason is INCORRECT.
D. If Assertion is INCORRECT but Reason is CORRECT.

Answer

To solve the question, we need to analyze both the assertion and the reason provided, and determine their correctness and relationship.

### Step 1: Analyze the Assertion
The assertion states that the addition of bromine to trans-but-2-ene yields meso-2,3-dibromobutane.

- **Trans-but-2-ene** is an alkene with the following structure:
```
CH3
|
CH3-CH=CH-CH3
|
Br
```
- When bromine (Br2) is added to trans-but-2-ene, a cyclic bromonium ion is formed as an intermediate. The addition of bromine occurs in a way that the bromine atoms add to opposite sides of the double bond, leading to the formation of a meso compound due to the symmetry of the resulting molecule.

Thus, the assertion is **correct**.

### Step 2: Analyze the Reason
The reason states that bromine addition to an alkene is a nucleophilic addition.

- While it is true that bromine can act as a nucleophile, the mechanism of bromine addition to alkenes is better described as an electrophilic addition rather than a nucleophilic addition. The bromine molecule (Br2) undergoes polarization when it approaches the alkene, leading to the formation of a bromonium ion, which is an electrophilic species.

Thus, the reason is **incorrect**.

### Step 3: Determine the Relationship
Now we can summarize our findings:
- The assertion is **correct**.
- The reason is **incorrect**.

### Conclusion
Based on the analysis:
- The correct option is **(c)**: Assertion is CORRECT but Reason is INCORRECT.