Which of the following is correct?

Options

A. `"_1H^1` and `"_2He^4` are isotopes
B. `"_6C^14` and `"_7N^14` are isotopes
C. `"_(19)K^39` and `"_(20)Ca^(40)` are isotopes.
D. `"_9F^19` and `"_11Na^24 `are isodlaphers

Answer

To determine which of the statements regarding isotopes is correct, we need to understand the definition of isotopes and analyze the given elements based on their atomic structure.

### Step-by-Step Solution:

1. **Understand the Definition of Isotopes**:
- Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have the same atomic number but different mass numbers.

2. **Analyze the Given Elements**:
- Let's examine the examples mentioned in the transcript:
- **1H1 (Hydrogen)**: This has 1 proton and 0 neutrons (mass number = 1).
- **2H1 (Deuterium)**: This has 1 proton and 1 neutron (mass number = 2).
- **Carbon (C)**: The common isotope is 6C12, which has 6 protons and 6 neutrons (mass number = 12).
- **Nitrogen (N)**: The common isotope is 7N14, which has 7 protons and 7 neutrons (mass number = 14).
- **Potassium (K)**: The common isotope is 19K39, which has 19 protons and 20 neutrons (mass number = 39).

3. **Identify Isotopes**:
- From the examples:
- 1H1 and 2H1 are isotopes of Hydrogen because they have the same number of protons (1) but different numbers of neutrons (0 and 1).
- Carbon and Nitrogen are not isotopes of each other as they have different atomic numbers (6 and 7).
- Potassium isotopes would be different if they have different mass numbers, but they are not isotopes of each other.

4. **Check for Isodifers**:
- Isodifers are different elements that have the same number of protons and neutrons combined but are not isotopes.
- For example, 9F19 (Fluorine) and 11N24 (Sodium) are not isotopes since they have different atomic numbers.

5. **Conclusion**:
- Based on the analysis, none of the examples given in the question are isotopes of each other. The correct statement is that isotopes must have the same number of protons but different numbers of neutrons.

### Final Answer:
None of the given statements are correct regarding isotopes.