Which of the following statements is not true for `H^(1), H^2` and `H^3`?

Options

A. They have similar electronic configuration.
B. They exist in nature in the ratio 1:2:3.
C. Their atomic masses are in the ratio 1: 2: 3.
D. They are all isotopes of hydrogen.

Explanation

To determine which statement is not true for the isotopes of hydrogen (H^1, H^2, and H^3), we need to analyze the properties of these isotopes.

### Step-by-Step Solution:

1. **Identify the Isotopes**:
- H^1 (Protium) has 1 proton and 0 neutrons.
- H^2 (Deuterium) has 1 proton and 1 neutron.
- H^3 (Tritium) has 1 proton and 2 neutrons.

2. **Understand the Concept of Isotopes**:
- Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Therefore, they have the same atomic number but different mass numbers.

3. **Evaluate Each Statement**:
- **Statement 1**: "They have similar electronic configuration."
- Since all three isotopes have the same number of electrons (1), they will have the same electronic configuration (1s^1). This statement is true.

- **Statement 2**: "They exist in nature in the ratio 1:2:3."
- The natural abundance of these isotopes is approximately:
- Protium (H^1): 99.984%
- Deuterium (H^2): 0.016%
- Tritium (H^3): ~10^-15%
- The ratio is not 1:2:3; it is actually about 6400:1 for Protium to Deuterium, and Tritium is negligible. This statement is false.

- **Statement 3**: "Their atomic masses are in the ratio 1:2:3."
- The mass numbers of the isotopes are 1 (for H^1), 2 (for H^2), and 3 (for H^3). Thus, the atomic masses are indeed in the ratio 1:2:3. This statement is true.

- **Statement 4**: "They are all isotopes of hydrogen."
- All three are indeed isotopes of hydrogen, so this statement is true.

4. **Conclusion**:
- The statement that is not true is **Statement 2**: "They exist in nature in the ratio 1:2:3."

### Final Answer:
The statement that is not true for H^1, H^2, and H^3 is: "They exist in nature in the ratio 1:2:3."

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