Sodium chloride imparts a yellow colour to the Bunsen flame .This can be interpreted due to the

Options

A. Sublimation of metallic sodium to give yellow vapour
B. Photosenstivity of sodium
C. Low ionization potential of sodium
D. Emission of excess of energy absorbed as a radiation in the visible region

Answer

To solve the question regarding why sodium chloride imparts a yellow color to the Bunsen flame, we can break down the explanation step by step.

### Step-by-Step Solution:

1. **Understanding the Context**:
- Sodium chloride (NaCl) is a compound that contains sodium (Na), which is an alkali metal. When NaCl is introduced into a Bunsen flame, it produces a characteristic yellow color.

2. **Behavior of Alkali Metals in Flame**:
- Alkali metals, including sodium, have valence electrons that can be excited to higher energy levels when they absorb energy from the flame.

3. **Energy Absorption**:
- When sodium chloride is heated in the Bunsen flame, the energy from the flame is absorbed by the valence electrons of sodium. This causes the electrons to move from a lower energy level (E1) to a higher energy level (E2).

4. **Energy Emission**:
- After a short period, the excited electrons will return to their original lower energy level (E1). As they do so, they release the absorbed energy in the form of light.

5. **Color of the Emitted Light**:
- The energy emitted corresponds to a specific wavelength of light. For sodium, this wavelength falls within the visible spectrum and is perceived as yellow light.

6. **Conclusion**:
- Thus, the yellow color observed in the flame is due to the emission of excess energy absorbed by the sodium electrons as they transition back to their lower energy state. This corresponds to option D: "emission of excess of energy absorbed as a radiation in the visible region."

### Final Answer:
The correct interpretation of why sodium chloride imparts a yellow color to the Bunsen flame is due to **option D: emission of excess of energy absorbed as a radiation in the visible region**.

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