Which of the following nuclear reactions will generate an isotope ?

Options

A. `beta -` particle emission
B. Neutron particle emission
C. Position emission
D. `alpha-` particle emission

Answer

To determine which nuclear reaction generates an isotope, we need to understand the definition of isotopes and the effects of different types of nuclear reactions.

### Step-by-Step Solution:

1. **Understand Isotopes**:
- Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have the same atomic number but different mass numbers.

2. **Identify Types of Nuclear Reactions**:
- There are several types of nuclear reactions, including:
- Neutron emission
- Beta particle emission
- Positron emission
- Alpha particle emission

3. **Analyze Neutron Emission**:
- In neutron emission, a neutron is released from the nucleus. Since the number of protons remains unchanged, the atomic number stays the same, but the mass number decreases by one. This reaction can lead to the formation of an isotope of the original element.

4. **Analyze Beta Particle Emission**:
- In beta decay, a neutron in the nucleus is converted into a proton and an electron (beta particle) is emitted. This increases the atomic number by one, resulting in a different element, not an isotope.

5. **Analyze Positron Emission**:
- In positron emission, a proton is converted into a neutron and a positron is emitted. This decreases the atomic number by one, resulting in a different element, not an isotope.

6. **Analyze Alpha Particle Emission**:
- In alpha decay, an alpha particle (which consists of 2 protons and 2 neutrons) is emitted. This decreases the atomic number by 2 and the mass number by 4, resulting in a different element, not an isotope.

7. **Conclusion**:
- Among the reactions analyzed, only neutron emission results in the formation of an isotope, as it does not change the number of protons in the nucleus.

### Final Answer:
The nuclear reaction that generates an isotope is **neutron emission**.