In the atomic spectrum of hydrogen, the spectral lines pertaining to electronic transition of n = 4 to n = 2 refers to

Options

A. Lyman lines
B. Balmer lines
C. Paschen lines
D. Brackett lines.

Explanation

To solve the question regarding the spectral lines in the atomic spectrum of hydrogen that pertain to the electronic transition from n = 4 to n = 2, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Energy Levels**:
In a hydrogen atom, electrons occupy different energy levels denoted by quantum numbers (n). The energy levels are quantized, meaning electrons can only exist at specific distances from the nucleus.

2. **Identifying the Transition**:
The question specifies a transition from n = 4 to n = 2. This means an electron is moving from a higher energy level (n = 4) to a lower energy level (n = 2).

3. **Determining the Series**:
The transitions in the hydrogen spectrum are categorized into series based on the final energy level:
- **Lyman Series**: Transitions to n = 1 (ultraviolet region)
- **Balmer Series**: Transitions to n = 2 (visible region)
- **Paschen Series**: Transitions to n = 3 (infrared region)
- **Brackett Series**: Transitions to n = 4 (infrared region)
- **Pfund Series**: Transitions to n = 5 (infrared region)

4. **Identifying the Correct Series for the Given Transition**:
Since the transition from n = 4 to n = 2 ends at n = 2, it falls under the **Balmer Series**. The Balmer series involves transitions where the final energy level is n = 2.

5. **Conclusion**:
Therefore, the spectral lines pertaining to the electronic transition from n = 4 to n = 2 in the atomic spectrum of hydrogen refer to the **Balmer Series**.

### Final Answer:
The spectral lines pertaining to the electronic transition from n = 4 to n = 2 refer to the **Balmer Series**.

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