Question

In which of the following systems 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

Answer 1

The correct option is (a) doubly ionized lithium.

Explanation:

Radius of first orbit r ∝ 1/Z

for doubly ionized lithium Z ( = 3) will be maximum, hence for doubly ionized lithium, r will be minimum.