Two atoms are said to be isobars, if

Options

A. they have some atomic number but different mass number
B. they have same number of electrons but different numbers of neutrons
C. they have same number of neutrons but different number of electrons
D. None of these

Answer

**Step-by-Step Text Solution:**

1. **Definition of Isobars**: Two atoms are said to be isobars if they have the same mass number but different atomic numbers. This means that the total number of protons and neutrons in the nucleus of each atom is the same, but the number of protons (which defines the atomic number) is different.

2. **Understanding Mass Number and Atomic Number**:
- The **mass number** (A) is the total number of protons and neutrons in an atom's nucleus.
- The **atomic number** (Z) is the number of protons in the nucleus of an atom, which determines the element.

3. **Example of Isobars**:
- A common example of isobars is Argon-40 (₁₈Ar) and Calcium-40 (₂₀Ca). Both have a mass number of 40, but Argon has 18 protons and Calcium has 20 protons. Thus, they are isobars.

4. **Conclusion**: Therefore, isobars are characterized by having the same mass number but different atomic numbers.

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