In electron capture (radioactive process):

Options

A. a neutron is formed
B. a proton is consumed
C. `gamma` -ray emission take place
D. X-ray emission takes place

Answer

**Step-by-Step Solution:**

1. **Understanding Electron Capture:**
- Electron capture is a radioactive decay process where an electron from the innermost energy level is captured by a proton in the nucleus.
- This process converts the proton into a neutron, resulting in a decrease in the atomic number of the element.

2. **Change in Atomic and Mass Numbers:**
- In electron capture, the atomic number (Z) decreases by 1 because a proton is converted into a neutron.
- The mass number (A) remains unchanged since the total number of nucleons (protons + neutrons) does not change; only the type of nucleon changes.

3. **Formation of Neutron:**
- The equation for electron capture can be represented as:
\[ p + e^- \rightarrow n \]
- Here, \(p\) represents a proton, \(e^-\) is the captured electron, and \(n\) is the resulting neutron.

4. **Gamma Ray Emission:**
- After electron capture, the nucleus may be in an excited state and can release energy in the form of gamma rays.
- Gamma emission does not change the atomic number or mass number.

5. **X-ray Emission:**
- X-rays are not directly related to electron capture. They are produced when high-energy electrons collide with a metal target in an X-ray tube.
- This process is distinct from the nuclear changes occurring during electron capture.

6. **Conclusion:**
- In summary, during electron capture, a proton is consumed, a neutron is formed, and gamma rays may be emitted. The atomic number decreases by one, while the mass number remains the same.