Assertion : 2,3-Dimethylbut-2-ene is more stable than but-2-ene.
Reason : Six hyperconjugation structures can be written for 2, 3-dimethylbut-2- ene while but-2-ene has twelve.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze the assertion and reason provided regarding the stability of 2,3-dimethylbut-2-ene compared to but-2-ene.

### Step-by-Step Solution:

1. **Identify the Structures**:
- Draw the structure of **2,3-dimethylbut-2-ene**:
- It has a double bond between the second and third carbon atoms, with methyl groups attached to the second and third carbon.
- Structure:
```
CH3
|
CH3-C=C-CH3
```
- Draw the structure of **but-2-ene**:
- It has a double bond between the second and third carbon atoms, with hydrogen atoms filling the remaining valences.
- Structure:
```
CH3-CH=C-CH3
```

2. **Count the Alpha Hydrogens**:
- **2,3-Dimethylbut-2-ene**:
- The alpha carbons (the carbons adjacent to the double bond) are the second and third carbons.
- Each of these carbons has 3 alpha hydrogens (from the methyl groups).
- Total alpha hydrogens = 3 (from C2) + 3 (from C3) = 6 alpha hydrogens.
- **But-2-ene**:
- The alpha carbons are again the second and third carbons.
- Each of these carbons has 3 alpha hydrogens.
- Total alpha hydrogens = 3 (from C2) + 3 (from C3) = 6 alpha hydrogens.

3. **Hyperconjugation**:
- Hyperconjugation refers to the interaction of electrons in a sigma bond with adjacent empty or partially filled p orbitals.
- The more alpha hydrogens present, the more hyperconjugation structures can be formed, leading to increased stability.
- Both compounds have the same number of alpha hydrogens (6), thus they should have similar hyperconjugation effects.

4. **Evaluate the Assertion and Reason**:
- **Assertion**: "2,3-Dimethylbut-2-ene is more stable than but-2-ene."
- This statement is **false** because both have the same number of alpha hydrogens and thus similar stability.
- **Reason**: "Six hyperconjugation structures can be written for 2,3-dimethylbut-2-ene while but-2-ene has twelve."
- This statement is also **false** because both have 6 alpha hydrogens and thus the same potential for hyperconjugation.

5. **Conclusion**:
- The assertion is false, and the reason is also false. Therefore, the correct answer is that both the assertion and reason are false.

### Final Answer:
Both assertion and reason are false.