Statement-I : Propene is more reactive than ethnc with `HCl`.
Because
Staement-II : Propene is more stable than ethene.

Answer

To analyze the statements provided in the question, we will break down the reasoning step by step.

### Step 1: Understand the Reactivity of Propene and Ethene with HCl
- **Propene (C3H6)** has the structure:
```
H2C=CH-CH3
```
- **Ethene (C2H4)** has the structure:
```
H2C=CH2
```
- When HCl reacts with these alkenes, a carbocation is formed.

### Step 2: Identify the Type of Carbocation Formed
- For **Propene**, the addition of HCl leads to the formation of a secondary carbocation:
```
H2C-CH(+)-CH3
```
- For **Ethene**, the addition of HCl leads to the formation of a primary carbocation:
```
H2C-CH(+)-H
```

### Step 3: Stability of Carbocations
- **Secondary carbocations** (like the one formed from propene) are more stable than **primary carbocations** (like the one formed from ethene) due to hyperconjugation and inductive effects.
- Therefore, the secondary carbocation formed from propene is more stable than the primary carbocation formed from ethene.

### Step 4: Conclusion on Reactivity
- Since propene forms a more stable carbocation compared to ethene when reacting with HCl, it is more reactive than ethene with HCl. Thus, **Statement-I** is correct.

### Step 5: Analyze the Stability of Propene and Ethene
- **Propene** has three alpha hydrogens (attached to the carbon adjacent to the double bond), while **Ethene** has none.
- The stability of alkenes is influenced by the number of alpha hydrogens due to hyperconjugation. More alpha hydrogens lead to greater stability.

### Step 6: Conclusion on Stability
- Since propene has more alpha hydrogens than ethene, **Statement-II** is also correct.

### Step 7: Evaluate the Relationship Between the Statements
- While both statements are correct, **Statement-II** does not provide a valid explanation for **Statement-I**. The reactivity of propene with HCl is due to the stability of the carbocation formed, not merely because propene is more stable than ethene.

### Final Answer
- **Statement-I** is correct: Propene is more reactive than ethene with HCl.
- **Statement-II** is correct: Propene is more stable than ethene.
- However, **Statement-II** is not the correct explanation for **Statement-I**.