How many among the following imparts colour to the Bunsen flame, when flame test is carried out?
`Ba, Mg, Ca, Be, Na, Sr,L`

Options

A. 5
B. 6
C. 7
D. 4

Answer

To determine how many of the given elements impart color to a Bunsen flame during a flame test, we need to analyze each element's ability to emit light when heated.

### Step-by-Step Solution:

1. **List the Elements**: The elements given are Ba (Barium), Mg (Magnesium), Ca (Calcium), Be (Beryllium), Na (Sodium), Sr (Strontium), and L (Lithium).

2. **Understand Flame Tests**: A flame test is used to identify the presence of certain metal ions based on the color they emit when heated in a flame. Not all metals produce a visible color.

3. **Identify Non-Color Producing Elements**:
- **Beryllium (Be)**: Does not impart color to the flame.
- **Magnesium (Mg)**: Does not impart color to the flame.

Both Be and Mg have tightly held electrons and do not easily get excited to emit light in the visible spectrum.

4. **Identify Color Producing Elements**:
- **Barium (Ba)**: Produces a green color.
- **Calcium (Ca)**: Produces an orange-red color.
- **Sodium (Na)**: Produces a bright yellow color.
- **Strontium (Sr)**: Produces a red color.
- **Lithium (L)**: Produces a crimson red color.

5. **Count the Color Producing Elements**:
- From the analysis, the elements that impart color to the flame are Ba, Ca, Na, Sr, and L.
- This gives us a total of 5 elements that produce color.

6. **Final Answer**: Therefore, the number of elements that impart color to the Bunsen flame is **5**.