Which of the following statement(s) is/are incorrect regarding `S_N 1` reaction?
I) Rearrangement is possible.
II) Proceeds with complete inversion of configuration.
III) Rate depends on polarity of solvent.
IV) The strength of the nucleophile is important in rate determining step.

Options

A. II,IV only
B. I, II, IV only
C. III only
D. I, II only

Answer

To determine which statements regarding the \( S_N 1 \) reaction are incorrect, let’s analyze each statement step by step.

### Step 1: Understanding \( S_N 1 \) Mechanism
The \( S_N 1 \) reaction involves two main steps:
1. Formation of a carbocation (rate-determining step).
2. Nucleophilic attack on the carbocation.

### Step 2: Evaluating Each Statement
**Statement I: Rearrangement is possible.**
- This statement is **true**. During the formation of the carbocation, if the carbocation is not stable, it can rearrange to form a more stable carbocation (e.g., through hydride or alkyl shifts).

**Statement II: Proceeds with complete inversion of configuration.**
- This statement is **incorrect**. \( S_N 1 \) reactions typically lead to a racemic mixture of products due to the planar nature of the carbocation, which allows the nucleophile to attack from either side, leading to both inversion and retention of configuration.

**Statement III: Rate depends on polarity of solvent.**
- This statement is **true**. The rate of an \( S_N 1 \) reaction is influenced by the polarity of the solvent because a polar solvent stabilizes the carbocation and the leaving group, thus facilitating the reaction.

**Statement IV: The strength of the nucleophile is important in the rate-determining step.**
- This statement is **incorrect**. In an \( S_N 1 \) reaction, the rate-determining step is the formation of the carbocation, which does not depend on the nucleophile's strength. The nucleophile's strength becomes relevant after the carbocation is formed.

### Conclusion
Based on the analysis:
- **Incorrect statements**: II and IV.
- **Correct statements**: I and III.

### Final Answer
The incorrect statements regarding \( S_N 1 \) reactions are:
- II) Proceeds with complete inversion of configuration.
- IV) The strength of the nucleophile is important in the rate determining step.