Practice portal › Atoms › Bohr Model of the Hydrogen Atom

The radius of hydrogen atom in its ground state is 5.3×10⁻¹¹ m. After collision with an electron it is found to have a radius of 21.2×10⁻¹¹ m. What is the principal quantum number n of the final state of the atom?

Asked in CBSE AIPMT 1994 · Postulates, radius, speed and angular momentum

Answer: (2) n=2

Step-by-step solution

Given: rᵢ=5.3×10⁻¹¹ m at nᵢ=1, and r_f=21.2×10⁻¹¹ m.

Idea: for hydrogen rₙ∝ n², so (r_f)/(rᵢ)=(n_f²)/(nᵢ²).

(21.2×10⁻¹¹)/(5.3×10⁻¹¹)=4, so n_f²=4.

n_f=2.

Why the other options are wrong

More Bohr Model of the Hydrogen Atom questionsAll Bohr Model of the Hydrogen Atom questions →

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.

Practise this with a timer