Flame test is not given by

Options

A. `Mg^(2+)` ions
B. `Ba^(2+)` ion
C. `Be^(2+)` ions
D. `Ca^(2+) `ions

Answer

To determine which metal ions do not give a flame test, we need to analyze the properties of the given alkaline earth metals and their behavior in a flame test.

### Step-by-Step Solution:

1. **Understanding Flame Test**:
- The flame test is a qualitative analysis technique used to identify the presence of certain metal ions based on the color they impart to a flame when heated.

2. **Identifying the Metal Ions**:
- The question provides us with four alkaline earth metal ions: Barium (Ba²⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺), and Beryllium (Be²⁺).

3. **Analyzing Each Metal Ion**:
- **Barium (Ba²⁺)**: When heated, barium imparts an apple green color to the flame. Therefore, it does give a flame test.
- **Calcium (Ca²⁺)**: Calcium gives a brick red color to the flame, indicating it also gives a flame test.
- **Magnesium (Mg²⁺)**: Magnesium does not impart any color to the flame because it has a high ionization energy. It requires a large amount of energy to excite its electrons, which is not available in a Bunsen burner flame. Thus, it does not give a flame test.
- **Beryllium (Be²⁺)**: Similar to magnesium, beryllium also does not impart any color to the flame due to its high ionization energy, which prevents its electrons from being excited to higher energy levels.

4. **Conclusion**:
- The metal ions that do not give a flame test are Magnesium (Mg²⁺) and Beryllium (Be²⁺).

### Final Answer:
- The flame test is not given by Magnesium (Mg²⁺) and Beryllium (Be²⁺).