Assertion. Propene is more reactive than ethene towards electrophilic addition reactions
Reason. Hyperconjugation effect of the `CH_3` group increases the electron density in the double bond

Options

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

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "Propene is more reactive than ethene towards electrophilic addition reactions."

- **Explanation**: Electrophilic addition reactions involve the addition of an electrophile to a double bond. The reactivity of alkenes in these reactions is influenced by the stability of the carbocation intermediate formed during the reaction.

### Step 2: Analyze the Structure of Propene and Ethene
- **Propene** has the structure CH3-CH=CH2, while **Ethene** has the structure CH2=CH2.
- When an electrophile approaches, a carbocation is formed. In propene, the carbocation can be stabilized by hyperconjugation due to the presence of the CH3 group.

### Step 3: Stability of Carbocations
- The stability of carbocations increases with the number of alkyl groups attached to the positively charged carbon.
- In propene, the carbocation formed (if the electrophile adds to the terminal carbon) can be stabilized by three hyperconjugative interactions from the three hydrogen atoms of the CH3 group.
- In contrast, the carbocation formed from ethene (if the electrophile adds to either carbon) has no alkyl groups to stabilize it.

### Step 4: Conclusion on Reactivity
- Since propene forms a more stable carbocation than ethene, it follows that propene is more reactive towards electrophilic addition reactions.

### Step 5: Analyze the Reason
The reason states that "Hyperconjugation effect of the CH3 group increases the electron density in the double bond."

- **Explanation**: Hyperconjugation involves the delocalization of electrons from the adjacent C-H bonds to the empty p-orbital of the carbocation, which increases the electron density in the double bond and stabilizes the carbocation.

### Final Conclusion
- Both the assertion and the reason are true. The reason correctly explains why propene is more reactive than ethene towards electrophilic addition reactions.

### Summary
- **Assertion**: True
- **Reason**: True
- **Explanation**: The hyperconjugation effect of the CH3 group in propene increases the electron density in the double bond, making propene more reactive than ethene.

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