To solve the question comparing the intrinsic stability and reactivity of 1,3-pentadiene and 1,4-pentadiene, we will analyze their structures and reactions step by step.
### Step 1: Understand the Structures
1,3-pentadiene has the following structure:
- It contains a conjugated system of double bonds (C=C-C=C), where the double bonds are separated by a single bond.
- The structure can be represented as: CH2=CH-CH=CH-CH3.
1,4-pentadiene has the following structure:
- It contains isolated double bonds (C=C-C-C), where the double bonds are not adjacent to each other.
- The structure can be represented as: CH2=CH-CH2-CH=CH2.
### Step 2: Analyze Stability
- **Conjugated Dienes (1,3-pentadiene)**: Conjugated systems are generally more stable due to resonance. The pi electrons can delocalize over the adjacent double bonds, which lowers the overall energy of the molecule.
- **Isolated Dienes (1,4-pentadiene)**: Isolated double bonds do not benefit from resonance stabilization. Therefore, they are generally less stable compared to conjugated systems.
**Conclusion on Stability**: 1,3-pentadiene is more stable than 1,4-pentadiene.
### Step 3: Analyze Reactivity with HI
- When 1,3-pentadiene reacts with HI:
- The double bond can react to form a more stable product due to the formation of a secondary carbocation, which is stabilized by resonance.
- When 1,4-pentadiene reacts with HI:
- The reaction will also form a carbocation, but since the double bonds are isolated, the stabilization is only due to the inductive effect of alkyl groups, not resonance.
**Conclusion on Reactivity**: 1,3-pentadiene is more reactive than 1,4-pentadiene due to the formation of a more stable carbocation during the reaction.
### Final Conclusion
Based on the analysis:
- 1,3-pentadiene is more stable and more reactive than 1,4-pentadiene.
### Correct Statement
The correct statement is: **1,3-pentadiene is more stable and more reactive than 1,4-pentadiene.**
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