Bohr's model is applicable to which ion?

Options

A. `H^+`
B. `He^+`
C. `Li^+`
D. `Na^+`

Answer

**Step-by-Step Solution:**

1. **Understanding Bohr's Model**: Bohr's model of the atom is primarily applicable to hydrogen-like (one-electron) systems. This means that it can be used for any atom or ion that has only one electron.

2. **Identifying One-Electron Systems**: The question asks which ion Bohr's model is applicable to. We need to identify ions that have only one electron. The simplest example is hydrogen (H), which has one electron.

3. **Considering Other Ions**: We can also consider other ions that may have only one electron after losing some electrons:
- **Helium Ion (He⁺)**: Helium has an atomic number of 2 and normally has 2 electrons. If it loses one electron, it becomes He⁺, which has 1 electron. Hence, it is a one-electron system.
- **Lithium Ion (Li²⁺)**: Lithium has an atomic number of 3 and normally has 3 electrons. If it loses 2 electrons, it becomes Li²⁺, which has 1 electron. Thus, it is also a one-electron system.
- **Beryllium Ion (Be³⁺)**: Beryllium has an atomic number of 4 and normally has 4 electrons. If it loses 3 electrons, it becomes Be³⁺, which has 1 electron. Therefore, it is a one-electron system as well.

4. **Conclusion**: Since Bohr's model is applicable to one-electron systems, it can be applied to:
- Hydrogen (H)
- Helium ion (He⁺)
- Lithium ion (Li²⁺)
- Beryllium ion (Be³⁺)

5. **Final Answer**: The ions that Bohr's model is applicable to are He⁺, Li²⁺, and Be³⁺.