An element E loses one `alpha` and two `beta`-particles in three successive stages. The resulting element will be

Options

A. an isobar of E
B. an isotone of E
C. an isotope of E
D. E itself

Explanation

To solve the problem step by step, we will analyze the changes that occur when element E loses one alpha particle and two beta particles.

### Step 1: Understand the changes caused by alpha and beta decay

1. **Alpha Decay**: When an element loses an alpha particle (which is \( ^4_2He \)), the mass number decreases by 4 and the atomic number decreases by 2.
- If the original element E has a mass number \( A \) and atomic number \( Z \), after losing one alpha particle, the new mass number will be \( A - 4 \) and the new atomic number will be \( Z - 2 \).

2. **Beta Decay**: When an element loses a beta particle (which is \( ^0_{-1}e \)), there is no change in the mass number, but the atomic number increases by 1.
- After the first beta decay, the mass number remains \( A - 4 \) and the atomic number becomes \( Z - 2 + 1 = Z - 1 \).

3. **Second Beta Decay**: Losing another beta particle again results in no change in the mass number, but the atomic number increases by 1 again.
- After the second beta decay, the mass number remains \( A - 4 \) and the atomic number becomes \( Z - 1 + 1 = Z \).

### Step 2: Write the final result after all decays

After losing one alpha particle and two beta particles, the resulting element will have:
- Mass number: \( A - 4 \)
- Atomic number: \( Z \)

### Step 3: Identify the resulting element

The resulting element has the same atomic number \( Z \) as the original element E but a different mass number \( A - 4 \). Elements with the same atomic number but different mass numbers are known as **isotopes**.

### Conclusion

Thus, the resulting element after losing one alpha particle and two beta particles is an **isotope** of the original element E.

### Final Answer:
The resulting element will be an **isotope of E**.

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