Which of the following is not a pseudohalide

Options

A. `RCOO^(-)`
B. `CN^(-)`
C. `CNO^(-)`
D. `N_3^(-)`

Answer

To determine which of the given options is not a pseudohalide, we first need to understand what a pseudohalide is. Pseudohalides are ions that consist of two or more electronegative atoms, with at least one of them being nitrogen. They exhibit similar properties to halide ions.

### Step-by-Step Solution:

1. **Define Pseudohalides**:
- Pseudohalides are ions that contain two or more electronegative atoms, with at least one being nitrogen. They mimic the behavior of halides.

2. **Identify Common Pseudohalides**:
- Common examples of pseudohalides include:
- Cyanide (CN⁻)
- Thiocyanate (SCN⁻)
- Azide (N₃⁻)
- Isocyanate (NCO⁻)

3. **Analyze the Given Options**:
- Without the specific options provided in the question, we would typically analyze each option to see if it fits the definition of a pseudohalide.
- Check if the ion contains nitrogen and consists of two or more electronegative atoms.

4. **Determine the Odd One Out**:
- After analyzing each option, if one of the ions does not contain nitrogen or does not fit the criteria of having two or more electronegative atoms, that would be the answer to the question.

5. **Conclude**:
- The ion that does not meet the criteria for being a pseudohalide is the answer to the question.