Assertion (A) . Pent-1-ene and pent-2-ene are position isomers.
Reason (R). Position isomers differ in the position of functional group or a substituent.

Options

A. Both A and R are correct and R is the correct explanation of A
B. Both A and R are correct but R is not the correct explanation of As
C. both A and R are not correct
D. A is not correct but R is correct

Explanation

To solve the assertion and reason question regarding pent-1-ene and pent-2-ene being position isomers, we will follow these steps:

### Step 1: Define Position Isomers
Position isomers are compounds that have the same molecular formula but differ in the position of a functional group or substituent in their structure.

### Step 2: Identify the Compounds
The compounds in question are pent-1-ene and pent-2-ene. Both of these compounds have the same molecular formula, which is C5H10.

### Step 3: Draw the Structures
- **Pent-1-ene**: The double bond is located at the first carbon. Its structure can be represented as:
```
CH2=CH-CH2-CH2-CH3
```
- **Pent-2-ene**: The double bond is located at the second carbon. Its structure can be represented as:
```
CH3-CH=CH-CH2-CH3
```

### Step 4: Analyze the Structures
From the structures drawn, we can see that:
- Pent-1-ene has the double bond between the first and second carbon.
- Pent-2-ene has the double bond between the second and third carbon.

### Step 5: Conclusion on Assertion and Reason
Since both compounds have the same molecular formula (C5H10) but differ in the position of the double bond (which acts as a functional group), they are indeed position isomers.

- **Assertion (A)**: Pent-1-ene and pent-2-ene are position isomers. (True)
- **Reason (R)**: Position isomers differ in the position of functional group or a substituent. (True)

### Final Answer
Both the assertion and the reason are correct, and the reason correctly explains the assertion. Therefore, the correct option is that both assertion and reason are correct, and the reason is the correct explanation of the assertion.

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