The halogen atom in `RX` can easily be replaced by nucleophiles such as :

Options

A. `NO_2^(Ө)`
B. `RO^(Ө)`
C. `CN^(Ө)`
D. None

Explanation

To solve the question regarding which nucleophiles can replace the halogen atom in `RX`, we will analyze the nature of nucleophiles and their ability to displace halogens.

### Step-by-Step Solution:

1. **Understanding Nucleophiles**:
- A nucleophile is a species that donates an electron pair to an electrophile to form a chemical bond. Nucleophiles are typically negatively charged or neutral species with lone pairs of electrons.

2. **Identifying the Halogen in RX**:
- In the compound `RX`, `R` represents a carbon chain or atom, and `X` represents a halogen (such as Cl, Br, or I). The halogen is usually a good leaving group due to its ability to stabilize the negative charge once it leaves.

3. **Analyzing the Given Nucleophiles**:
- The options provided are:
- NO⁻ (Nitrite ion)
- RO⁻ (Alkoxide ion)
- CN⁻ (Cyanide ion)

4. **Evaluating Each Nucleophile**:
- **NO⁻**: This is a strong nucleophile due to the presence of a lone pair of electrons on nitrogen, which can readily donate to the electrophilic carbon in `RX`.
- **RO⁻**: Alkoxide ions are also strong nucleophiles. The oxygen atom has lone pairs that can be donated, making it effective in displacing the halogen.
- **CN⁻**: The cyanide ion is a strong nucleophile as well, with the carbon atom having a lone pair that can attack the electrophilic carbon in `RX`.

5. **Conclusion**:
- All three nucleophiles (NO⁻, RO⁻, and CN⁻) are capable of replacing the halogen atom in `RX` due to their strong nucleophilic nature. Therefore, the correct answer is that all of these nucleophiles can replace the halogen.

### Final Answer:
The halogen atom in `RX` can easily be replaced by nucleophiles such as NO⁻, RO⁻, and CN⁻.

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