The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the

Options

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

Answer

To determine which spectral series of the hydrogen spectrum lies in the ultraviolet region, we can analyze the different series associated with hydrogen.

### Step-by-Step Solution:

1. **Understanding Spectral Series**:
The spectral lines of hydrogen are categorized into different series based on the transitions of electrons between energy levels. The main series are:
- Lyman series
- Balmer series
- Paschen series
- Brackett series
- Pfund series

2. **Identifying the Regions**:
- The **Lyman series** corresponds to transitions where electrons fall to the first energy level (n=1). This series emits ultraviolet radiation.
- The **Balmer series** corresponds to transitions to the second energy level (n=2) and emits visible light.
- The **Paschen series** corresponds to transitions to the third energy level (n=3) and emits infrared radiation.
- The **Brackett series** and **Pfund series** correspond to transitions to the fourth (n=4) and fifth (n=5) energy levels, respectively, and also emit infrared radiation.

3. **Wavelength Analysis**:
- The wavelength of light emitted in the Lyman series is less than 400 nm, placing it in the ultraviolet region.
- The Balmer series has wavelengths in the range of approximately 400 nm to 700 nm (visible region).
- The Paschen series and others have longer wavelengths (greater than 700 nm), placing them in the infrared region.

4. **Conclusion**:
Since the Lyman series is the only series that emits light in the ultraviolet region, we conclude that the spectral series of the hydrogen spectrum that lies in the ultraviolet region is the **Lyman series**.

### Final Answer:
The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the **Lyman series**.

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