The mechanism of SN1 reaction is given as :
`underset("pair")underset("Solvent Separated ion")(underset("lon pair")(R-X-R^(o+)X^(Theta)rarrR^(o+))"||"X^(Theta)overset(Y^(Theta))rarrR-Y+X^(Theta))`
A student writes general characteristics based on the given mechanism as :
(a) The reaction is favoured by weak nucleophiles.
(b) `R^(o+)` would be easily formed if the substituents are bulky.
(c) The reaction is accompanied by racemization.
Which observations are correct?

Options

A. (a) and (b)
B. (a), (b) and (c)
C. (a) and (c)
D. (b) and (d)

Explanation

To analyze the statements regarding the SN1 reaction mechanism, let's break down each statement step by step:

### Step 1: Understanding the SN1 Mechanism
- The SN1 reaction involves two main steps:
1. Formation of a carbocation (R⁺) from the substrate (R-X).
2. Nucleophilic attack on the carbocation by a nucleophile (Y) to form the product (R-Y).

### Step 2: Evaluating Statement (a)
- **Statement (a)**: "The reaction is favored by weak nucleophiles."
- In an SN1 mechanism, the formation of the carbocation is the rate-determining step. Weak nucleophiles are preferred because they do not compete with the carbocation formation and do not act as bases. Strong nucleophiles would favor an SN2 mechanism instead.
- **Conclusion**: This statement is **incorrect**.

### Step 3: Evaluating Statement (b)
- **Statement (b)**: "R⁺ would be easily formed if the substituents are bulky."
- Bulky substituents stabilize the carbocation through hyperconjugation and inductive effects. Therefore, if the substituents are bulky, the carbocation (R⁺) will be more stable and can form more easily.
- **Conclusion**: This statement is **correct**.

### Step 4: Evaluating Statement (c)
- **Statement (c)**: "The reaction is accompanied by racemization."
- The carbocation formed in an SN1 reaction is planar (sp² hybridized), allowing the nucleophile to attack from either side. This leads to the formation of both enantiomers, resulting in a racemic mixture.
- **Conclusion**: This statement is **correct**.

### Final Conclusion
- The correct observations based on the analysis are:
- Statement (a) is incorrect.
- Statement (b) is correct.
- Statement (c) is correct.

Thus, the correct observations are **(b) and (c)**.