An electron in excited hydrogen atom falls from fifth energy level to second energy level. In which of the following regions, the spectral line will be observed and is part of which series of the atomic spectrum?

Options

A. Visible, Balmer
B. Ultraviolet, Lyman
C. Infrared, Paschen
D. Infrared, Brackett

Explanation

To solve the problem of determining the spectral line observed when an electron in a hydrogen atom falls from the fifth energy level (n=5) to the second energy level (n=2), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Initial and Final Energy Levels**:
- The electron is transitioning from the fifth energy level (n_initial = 5) to the second energy level (n_final = 2).

2. **Determine the Series**:
- In the hydrogen atom, different series of spectral lines correspond to transitions between energy levels. The series are defined as follows:
- Lyman series: n_final = 1
- Balmer series: n_final = 2
- Paschen series: n_final = 3
- Brackett series: n_final = 4
- Since the final energy level in this case is 2, the transition falls under the **Balmer series**.

3. **Identify the Region of the Spectrum**:
- The Balmer series corresponds to transitions that result in the emission of visible light. Therefore, the spectral lines produced from this transition will be observed in the **visible region** of the electromagnetic spectrum.

4. **Conclusion**:
- The spectral line observed when the electron falls from n=5 to n=2 is part of the **Balmer series** and will be observed in the **visible region** of the spectrum.

### Final Answer:
The spectral line will be observed in the **visible region** and is part of the **Balmer series** of the atomic spectrum.

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