The number of steps involved in `S_(N)^(1)` and `S_(N)^(2)` mechanisms are given by the set -

Options

A. 1,2
B. 3,1
C. 2,1
D. 2,2

Answer

To determine the number of steps involved in the SN1 and SN2 mechanisms, we can analyze each mechanism step by step.

### Step 1: Understanding SN1 Mechanism
- **Definition**: SN1 stands for Unimolecular Nucleophilic Substitution.
- **Steps Involved**:
1. **Carbocation Formation**: The first step involves the departure of the leaving group (e.g., Cl in CH3Cl), resulting in the formation of a carbocation (CH3+).
2. **Nucleophile Attack**: In the second step, the nucleophile (OH-) attacks the carbocation, leading to the formation of the final product (CH3OH).

Thus, the SN1 mechanism involves **2 steps**.

### Step 2: Understanding SN2 Mechanism
- **Definition**: SN2 stands for Bimolecular Nucleophilic Substitution.
- **Steps Involved**:
1. **Single Step Mechanism**: In this mechanism, the nucleophile attacks the substrate from the backside of the leaving group, leading to a simultaneous bond formation and bond breaking. This results in the formation of a transition state where both the nucleophile and the leaving group are partially bonded to the carbon atom.

Thus, the SN2 mechanism involves **1 step**.

### Conclusion
- The number of steps involved in SN1 is **2 steps**.
- The number of steps involved in SN2 is **1 step**.

### Final Answer
The number of steps involved in SN1 and SN2 mechanisms are given by the set: {2, 1}.

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