`SN` reaction is given by these compounds, which have a nuclophilic group and a good leaving `EWG`. It should be stable after leaving with bonding pair of `overline(e)'s` and it should have high polarisability.
Nucliphilic aliphatic substituion reaction is mainly of two types `SN^(-1)` and `SN^(2). SN^(-1)` mechanism is a two step process. Reaction velocity of `SN^(-1)` depends only on the concentration of the subtrate. It proceeds via the formation of carbocation, optically active substrate gives `(o+)` and `(o-)` froms of the product.
In most of the cases, the product usually consists of `5-20%` inverted and `(95-80%)` racemised species. The more stable is the carbocation, the greater is the propotion of racemission. In solvolysis reaction, the more nucleophillic is the solvent, the greater is the proportion of inversion.
Which of the following will give `SN` reaction?

Options

A. `R-Br`
B. `R-N_(3)`
C. `R-O^(o+)H_(2)`
D. All

Explanation

To determine which compounds will undergo an SN reaction, we need to analyze the characteristics of each compound based on the criteria for SN reactions. The key points to consider are the presence of a nucleophilic group, a good leaving group, and the stability of the leaving group after it departs.

### Step-by-Step Solution:

1. **Identify the Compounds**:
We are given three compounds to analyze for their ability to undergo SN reactions.

2. **Analyze Compound A**:
- **Structure**: Alkyl halide (R-Br).
- **Leaving Group**: Bromine (Br) is a good leaving group due to its ability to stabilize the negative charge after leaving.
- **Electronegativity**: There is a significant electronegativity difference between carbon and bromine, leading to a partial positive charge on carbon.
- **Conclusion**: Compound A can undergo an SN reaction because it has a good leaving group (Br) that is stable after leaving.

3. **Analyze Compound B**:
- **Structure**: R-N3 (where N3 is the azide group).
- **Leaving Group**: The azide ion (N3-) is stable and can act as a good leaving group.
- **Electronegativity**: There is a difference in electronegativity between carbon and nitrogen, which allows for polarization.
- **Conclusion**: Compound B can also undergo an SN reaction due to the stable azide leaving group.

4. **Analyze Compound C**:
- **Structure**: R-OH (where OH is the hydroxyl group).
- **Leaving Group**: When the hydroxyl group leaves, it forms water (H2O), which is a stable molecule.
- **Electronegativity**: Oxygen is more electronegative than carbon, leading to a partial positive charge on carbon when the bond breaks.
- **Conclusion**: Compound C can undergo an SN reaction because water is a good leaving group and stable after leaving.

5. **Final Conclusion**:
Since all three compounds (A, B, and C) have good leaving groups that are stable after departure, they can all undergo SN reactions. Therefore, the answer is that all the compounds can give SN reactions.

### Final Answer:
**All of the above compounds can undergo SN reactions.**

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