Emission of `beta` -particle is equivatent to:

Options

A. increase of one proton only
B. decrease of one neutron only
C. both (a) and (b)
D. none of these

Answer

To solve the question regarding the emission of a beta particle, we need to understand what happens during beta decay.

### Step-by-Step Solution:

1. **Understanding Beta Particle Emission**:
- A beta particle is essentially an electron (β-) that is emitted from a nucleus during the decay of a neutron.

2. **Neutron Composition**:
- A neutron is made up of one proton and one electron (in terms of quarks, it's a combination of one up quark and two down quarks). However, for our purposes, we can consider the neutron as a neutral particle with an atomic mass of 1 and an atomic number of 0.

3. **Beta Decay Process**:
- During beta decay, a neutron in the nucleus transforms into a proton and emits a beta particle (electron). The reaction can be summarized as:
\[ n \rightarrow p + e^- + \bar{\nu} \]
- Here, \(n\) is the neutron, \(p\) is the proton, \(e^-\) is the emitted beta particle (electron), and \(\bar{\nu}\) is an antineutrino.

4. **Changes in Atomic Number and Mass**:
- When a neutron is converted into a proton:
- The atomic number increases by 1 (since a proton is added).
- The atomic mass remains the same (since a neutron is replaced by a proton).

5. **Analyzing the Options**:
- Option 1: Increase of one proton only - **True** (since a neutron becomes a proton).
- Option 2: Decrease of one neutron only - **True** (since one neutron is converted to a proton).
- Option 3: Both A and B - **True** (since both changes occur).
- Option 4: None of this - **False**.

6. **Conclusion**:
- Therefore, the emission of a beta particle is equivalent to both an increase of one proton and a decrease of one neutron. The correct answer is option 3: **Both A and B**.