Bohr model cannot explain spectrum of

Options

A. the hydrogen atom only
B. all elements
C. any atomic or ionic species having one electron only
D. the hydrogen molecule

Explanation

**Step-by-Step Solution:**

1. **Understanding the Bohr Model**: The Bohr model of the atom was proposed by Niels Bohr in 1913. It describes the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus. The model was primarily developed to explain the spectrum of the hydrogen atom.

2. **Limitations of the Bohr Model**: The Bohr model is effective for hydrogen because it has only one electron. However, it has limitations when applied to multi-electron atoms or ions. The model does not take into account electron-electron interactions, which become significant in atoms with more than one electron.

3. **Spectra of Multi-Electron Atoms**: For atoms with more than one electron, the energy levels are affected by the presence of other electrons. This leads to complexities in the spectral lines that cannot be accurately predicted by the Bohr model.

4. **Conclusion**: Therefore, the Bohr model cannot explain the spectrum of multi-electron species (such as helium, lithium, etc.) or more complex atoms. It is only applicable to hydrogen-like atoms, which have a single electron.

**Final Answer**: The Bohr model cannot explain the spectrum of multi-electron atoms.

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