Which of the following types of radiation is not emitted by the electronic structure of atoms?

Options

A. Ultraviolet light
B. X-rays
C. Visible light
D. `gamma`-rays

Answer

To solve the question "Which of the following types of radiation is not emitted by the electronic structure of atoms?" we need to analyze the types of radiation listed: Ultraviolet rays, X-rays, visible rays, and gamma rays.

### Step-by-Step Solution:

1. **Understanding Electronic Structure of Atoms**:
- The electronic structure of an atom refers to the arrangement of electrons in various energy levels or orbits around the nucleus. When electrons transition between these energy levels, they can emit or absorb energy in the form of electromagnetic radiation.

2. **Types of Radiation Emitted by Electrons**:
- **Ultraviolet Rays**: When electrons jump from higher energy levels to lower ones, they can emit ultraviolet radiation.
- **X-rays**: These can also be emitted when electrons transition between energy levels, particularly in heavier elements where inner-shell electrons are involved.
- **Visible Rays**: The light that is visible to the human eye is emitted when electrons transition between energy levels within the visible spectrum.

3. **Gamma Rays**:
- Gamma rays are a form of electromagnetic radiation, but they are not emitted due to electronic transitions. Instead, they are produced during radioactive decay of atomic nuclei. This means that gamma rays originate from the nucleus of an atom, not from the electronic structure.

4. **Conclusion**:
- Since ultraviolet rays, X-rays, and visible rays are all emitted due to the electronic transitions of electrons in atoms, the type of radiation that is not emitted by the electronic structure of atoms is **gamma rays**.

### Final Answer:
The correct option is **D) Gamma rays**.

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