Question

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : The Bohr model is applicable to hydrogen and hydrogen-like atoms only. Reason R : The formulation of Bohr model does not include repulsive force between electrons. In the light of the above statements, choose the correct answer from the options given below :

• A. Both A and R are true but R is NOT the correct explanation of A.
• B. A is false but R is true.
• C. Both A and R are true and R is the correct explanation of A.
• D. A is true but R is false.

Hint:

The Bohr model is a foundational model in atomic physics but has limitations. Remember that it works well for single-electron systems because it neglects the complexities of electron-electron interactions. For multi-electron atoms, more sophisticated models like the quantum mechanical model are necessary.

Answer 1

The Correct Option is C

The question presents a statement and a justification concerning the Bohr model.

• Statement (A): The Bohr model is applicable exclusively to hydrogen and hydrogen-like atoms.
• Justification (R): The Bohr model's formulation does not incorporate the repulsive forces between electrons.

Analysis of both statements follows:

1. Analyzing Statement (A):
   • Introduced by Niels Bohr in 1913, the Bohr model describes the hydrogen atom or hydrogen-like ions (e.g., He⁺, Li²⁺) that possess only one electron. It incorporates the quantization of angular momentum and yields expressions for the energy levels of these single-electron systems. The model's efficacy is confined to single-electron systems because it omits electron-electron interactions, which are significant in atoms with multiple electrons.
2. Analyzing Justification (R):
   • The Bohr model postulates that electrons orbit the nucleus in defined paths, disregarding repulsive forces among multiple electrons. Its focus is solely on the electrostatic attraction between a single electron and the positively charged nucleus. This omission renders it unsuitable for multi-electron atoms where inter-electronic repulsions play a crucial role.

Comparison with provided options:

• Option 1: Both A and R are accurate, but R does not correctly explain A.
• Option 2: A is inaccurate, but R is accurate.
• Option 3: Both A and R are accurate, and R correctly explains A. (Correct Choice)
• Option 4: A is accurate, but R is inaccurate.

Conclusion: Both the statement and the justification are valid. Crucially, the justification accurately elucidates the limitation of the Bohr model to hydrogen and hydrogen-like atoms. Therefore, the correct selection is: Both A and R are accurate and R correctly explains A.