Question

For which of the following species Bohr’s theory is not applicable?

• A. \(Be^{3+}\)
• B. \(Li^{2+}\)
• C. \(He^{2+}\)
• D. \(H\)

Hint:

Bohr model works only for single-electron systems.

Answer 1

The Correct Option is C

Concept: Bohr’s theory applies to one-electron (hydrogen-like) species.

Step 1: Check electrons.
\[ Be^{3+} \rightarrow 1 \text{ electron} \] \[ Li^{2+} \rightarrow 1 \text{ electron} \] \[ H \rightarrow 1 \text{ electron} \] \[ He^{2+} \rightarrow 0 \text{ electron} \]

Step 2: Conclusion.
Bohr’s model is not applicable when no electron exists.