Question

In which of the following system, will the radius of the first orbit (n=1) be minimum?

(a) Doubly ionized lithium

(b) Singly ionized helium

(c) Deuterium atom

(d) Hydrogen atom

I got this question in an online interview.

This interesting question is from Alpha-Particle Scattering and Rutherford’s Nuclear Model of Atom topic in portion Atoms of Physics – Class 12

Answer 1

Correct choice is (a) Doubly ionized lithium

Best explanation: The equation is given as:

r = \(\frac {h^2}{2\pi^2 m k Z e^2}\)

Hence, of the given atoms/ions, (Z = 3) is maximum for doubly ionized lithium, so the radius of its first orbit is minimum.