The number of electrons in an element with atomic number X and mass number Y will be

Options

A. X - Y
B. Y-X
C. X + Y
D. X

Answer

To determine the number of electrons in an element with atomic number \( X \) and mass number \( Y \), we can follow these steps:

### Step-by-Step Solution:

1. **Understand Atomic Number and Mass Number**:
- The atomic number \( X \) of an element represents the number of protons in the nucleus of an atom of that element.
- The mass number \( Y \) is the total number of protons and neutrons in the nucleus.

2. **Identify the Relationship**:
- In a neutral atom, the number of electrons is equal to the number of protons. This means that for a neutral atom, the number of electrons is also equal to the atomic number \( X \).

3. **Conclusion**:
- Therefore, if the element is neutral, the number of electrons in the element is equal to the atomic number \( X \).

### Final Answer:
The number of electrons in an element with atomic number \( X \) and mass number \( Y \) is \( X \).

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