The metal ion which does not give any flame colouration is-

Options

A. `Li^(+)`
B. `Be^(+2)`
C. `Na^(+)`
D. `K^(+)`

Answer

To determine which metal ion does not give any flame coloration, we can analyze the flame test properties of the given metal ions: Lithium (Li⁺), Beryllium (Be²⁺), Sodium (Na⁺), and Potassium (K⁺).

### Step-by-Step Solution:

1. **Understanding Flame Coloration**:
- When metal ions are heated in a flame, their electrons can absorb energy and get excited to a higher energy level. As these electrons return to their ground state, they release energy in the form of light, which corresponds to specific colors.

2. **Identifying the Metal Ions**:
- The metal ions in question are:
- Lithium (Li⁺)
- Beryllium (Be²⁺)
- Sodium (Na⁺)
- Potassium (K⁺)

3. **Flame Test Results**:
- **Lithium (Li⁺)**: Produces a crimson red flame.
- **Sodium (Na⁺)**: Produces a bright yellow flame.
- **Potassium (K⁺)**: Produces a lilac or light purple flame.
- **Beryllium (Be²⁺)**: Does not produce any flame coloration.

4. **Conclusion**:
- Among the given metal ions, Beryllium (Be²⁺) does not give any flame coloration. Therefore, the answer to the question is Beryllium (Be²⁺).

### Final Answer:
The metal ion which does not give any flame coloration is **Beryllium (Be²⁺)**.