In the nuclear decay given below
`._Z^A X rarr ._(Z+1).^A Y rarr ._(Z-1)^(A - 4) B^** rarr ._(Z-1)^(A-4) B`,
the particle emitted in the sequence are

Options

A. `beta, alpha, gamma`
B. `gamma, beta, alpha`
C. `beta, gamma, alpha`
D. `alpha, beta, gamma`

Answer

To solve the problem of identifying the particles emitted during the nuclear decay sequence, we will analyze each step of the decay process based on the changes in atomic number (Z) and mass number (A).

### Step-by-Step Solution:

1. **Identify the Initial Element**:
We start with element \( X \) which has atomic number \( Z \) and mass number \( A \).

2. **First Decay: \( X \rightarrow Y \)**:
- The decay results in element \( Y \) with atomic number \( Z + 1 \) and mass number \( A \).
- Since the mass number remains the same and the atomic number increases by 1, this indicates that a **beta particle** (β) is emitted.
- **Conclusion**: The first particle emitted is a **beta particle**.

3. **Second Decay: \( Y \rightarrow B^* \)**:
- The next decay results in element \( B^* \) with atomic number \( Z - 1 \) and mass number \( A - 4 \).
- Here, the mass number decreases by 4 and the atomic number decreases by 2.
- This indicates that an **alpha particle** (α) is emitted, as alpha decay results in a decrease of 4 in mass number and 2 in atomic number.
- **Conclusion**: The second particle emitted is an **alpha particle**.

4. **Third Decay: \( B^* \rightarrow B \)**:
- The final decay results in element \( B \) with atomic number \( Z - 1 \) and mass number \( A - 4 \).
- There is no change in mass number or atomic number from \( B^* \) to \( B \).
- This indicates that a **gamma ray** (γ) is emitted, as gamma decay does not change the atomic or mass number.
- **Conclusion**: The third particle emitted is a **gamma ray**.

### Final Sequence of Emitted Particles:
- The sequence of particles emitted during the decay process is: **Beta particle (β), Alpha particle (α), Gamma ray (γ)**.

### Summary:
The correct order of particles emitted in the sequence is:
1. Beta particle (β)
2. Alpha particle (α)
3. Gamma ray (γ)