Assertion: The order of stability of carbocations is `3^(@) gt 2^(@) gt 1^(@)`
Reason: Carbon atom in carbocation is in `sp^(3)` state of hybridisation.

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 assertion and reason question regarding the stability of carbocations, let's break it down step by step.

### Step 1: Understand the Assertion
The assertion states that the order of stability of carbocations is:
\[ \text{3°} > \text{2°} > \text{1°} \]
This means that tertiary carbocations (3°) are more stable than secondary (2°), which in turn are more stable than primary (1°) carbocations.

### Step 2: Understand the Reason
The reason provided is that the carbon atom in a carbocation is in the \( sp^3 \) state of hybridization.

### Step 3: Analyze the Stability of Carbocations
- **Tertiary Carbocation (3°)**: A tertiary carbocation has three alkyl groups attached to the positively charged carbon. Alkyl groups donate electron density through the +I (inductive) effect and +H (hyperconjugation) effect, stabilizing the positive charge.

- **Secondary Carbocation (2°)**: A secondary carbocation has two alkyl groups. It is less stable than a tertiary carbocation but more stable than a primary carbocation due to the same effects, though to a lesser extent.

- **Primary Carbocation (1°)**: A primary carbocation has only one alkyl group attached, making it the least stable due to minimal stabilization from the +I and +H effects.

### Step 4: Analyze the Hybridization
In a carbocation:
- The carbon atom is **sp² hybridized**, not \( sp^3 \). This is because the carbon in a carbocation forms three sigma bonds and has a vacant p-orbital, leading to \( sp^2 \) hybridization (one s and two p orbitals hybridize).

### Step 5: Conclusion
- The assertion is **true**: The order of stability of carbocations is indeed \( 3° > 2° > 1° \).
- The reason is **false**: The carbon atom in a carbocation is \( sp^2 \) hybridized, not \( sp^3 \).

### Final Answer
Thus, the correct conclusion is that the assertion is true, but the reason is false.