Which one of the salts does not impart a colour to the flame or the flame test is not shown by

Options

A. LiCl
B. KI
C. `MgCl_2`
D. `CaCl_2`

Explanation

To determine which salt does not impart a color to the flame during a flame test, we can follow these steps:

### Step 1: Understand the Flame Test
The flame test is a qualitative analysis technique used to identify the presence of certain metal ions based on the color they emit when heated in a flame. When a metal salt is heated, its electrons can become excited and jump to a higher energy level. When they return to their original state, they release energy in the form of light, which corresponds to a specific color.

### Step 2: Identify the Metals in the Given Salts
The question requires us to analyze different salts. Common alkali earth metals include:
- Lithium (Li)
- Sodium (Na)
- Potassium (K)
- Calcium (Ca)
- Magnesium (Mg)
- Beryllium (Be)

### Step 3: Analyze Each Metal's Flame Color
- **Lithium (Li)**: Produces a crimson red flame.
- **Sodium (Na)**: Produces a bright yellow flame.
- **Potassium (K)**: Produces a violet flame.
- **Calcium (Ca)**: Produces a brick red flame.
- **Magnesium (Mg)**: Does not produce a flame color.
- **Beryllium (Be)**: Does not produce a flame color.

### Step 4: Conclusion
From the analysis, we can see that magnesium (Mg) and beryllium (Be) do not impart any color to the flame. Therefore, the salt that does not show a flame test is magnesium chloride (MgCl₂).

### Final Answer
The salt that does not impart a color to the flame is **MgCl₂**.

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