Question

What is the ratio of the atomic radius of the 5^th orbit in chlorine atom and 3^rd orbit in Helium atom?

(a) 153:50

(b) 50:153

(c) 153:100

(d) 100:153

This question was posed to me in exam.

Enquiry is from Bohr’s Model for Hydrogen Atom in section Structure of Atom of Chemistry – Class 11

Answer 1

Correct choice is (b) 50:153

To explain I would say: The atomic radius of an atom is given by the formula rn = 52.9n^2/Z pm, where rn is the radius of nth orbit of an atom and Z is the atomic number of that atom. The ratio of the atomic radius of the 5^th orbit in chlorine atom and 3^rd orbit in Helium atom is 25/17:9/2 = 50:153.