Which of the following process not lead to formation of isobars?

Options

A. `1 alpha` particle and `2 beta` particles are emitted
B. Positron emission
C. `beta` particle `(`_(-1)e^(0))`` emission
D. K-electron capture

Explanation

To determine which process does not lead to the formation of isobars, we need to understand what isobars are. Isobars are nuclides that have the same mass number (A) but different atomic numbers (Z).

Let's analyze the processes one by one:

1. **Emission of one alpha particle and two beta particles:**
- If we start with a nuclide represented as \( X \) with mass number \( A \) and atomic number \( Z \), the emission of one alpha particle (which has a mass number of 4 and atomic number of 2) will change the nuclide as follows:
- New mass number = \( A - 4 \)
- New atomic number = \( Z - 2 \)
- The emission of two beta particles (which do not change the mass number but increase the atomic number by 2) will further change it to:
- New mass number = \( A - 4 \)
- New atomic number = \( Z - 2 + 2 = Z \)
- Thus, the final nuclide has a mass number of \( A - 4 \) and atomic number \( Z \). Since the mass number has changed, this process does not lead to the formation of isobars.

2. **Emission of a positron:**
- A positron emission will decrease the atomic number by 1 while keeping the mass number the same:
- New mass number = \( A \)
- New atomic number = \( Z - 1 \)
- Since the mass number remains the same, this can lead to the formation of isobars.

3. **Emission of a beta particle:**
- A beta particle emission increases the atomic number by 1 while keeping the mass number the same:
- New mass number = \( A \)
- New atomic number = \( Z + 1 \)
- This also can lead to the formation of isobars.

4. **K electron capture:**
- In K electron capture, an electron is captured by the nucleus, which decreases the atomic number by 1 while keeping the mass number the same:
- New mass number = \( A \)
- New atomic number = \( Z - 1 \)
- This process can also lead to the formation of isobars.

**Conclusion:**
The only process that does not lead to the formation of isobars is the emission of one alpha particle and two beta particles. Therefore, the answer is:

**Answer: Emission of one alpha particle and two beta particles.**

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