Select the correct option

Options

A. `beta^+`decay occurs only when N/Z is too small for stability
B. `beta^-`decay occurs only when N/Z is too large for stability
C. In`beta^+`decay Z decreases by one,N increases by one
D. All of these

Answer

To solve the question regarding beta decay, we need to analyze the processes involved in beta minus decay and beta plus decay, and understand the conditions under which they occur based on the neutron-to-proton ratio (N/Z).

### Step-by-Step Solution:

1. **Understanding Beta Decay**:
- Beta decay occurs in two forms: beta minus (β-) decay and beta plus (β+) decay.
- In β- decay, a neutron is converted into a proton, emitting an electron (beta particle) and an antineutrino.
- In β+ decay, a proton is converted into a neutron, emitting a positron (the antiparticle of the electron) and a neutrino.

2. **Neutron-to-Proton Ratio (N/Z)**:
- The stability of a nucleus is influenced by the ratio of neutrons (N) to protons (Z).
- A stable nucleus typically has an optimal N/Z ratio. If the ratio is too high (more neutrons than protons), β- decay occurs to reduce the number of neutrons.
- Conversely, if the ratio is too low (more protons than neutrons), β+ decay occurs to increase the number of neutrons.

3. **Analyzing the Options**:
- **Option 1**: "Beta plus decay occurs only when N/Z is too small."
- This statement is correct. When the N/Z ratio is small, it indicates that there are too many protons relative to neutrons, leading to β+ decay.
- **Option 2**: "Beta minus decay occurs only when N/Z is too large."
- This statement is also correct. A large N/Z ratio indicates an excess of neutrons, which leads to β- decay.

4. **Conclusion**:
- Both options describe the conditions under which β+ and β- decay occur correctly.
- Therefore, the correct answer is that both statements are true regarding the conditions for beta decay.