Elements of the same mass number but of different atomic number are known as ……….

Options

A. Isotope
B. Isobar
C. Isoelectronic
D. None

Explanation

To solve the question "Elements of the same mass number but of different atomic number are known as ……….," we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Mass Number and Atomic Number**:
- The mass number of an element is the total number of protons and neutrons in its nucleus.
- The atomic number of an element is the number of protons in its nucleus, which also defines the element.

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