Question

What’s the radius of 1^st orbit of He^+ atom?

(a) 0.1058 nm

(b) 0.2156 nm

(c) 0.00529 nm

(d) 0.02645 nm

The question was asked in my homework.

The doubt is from Bohr’s Model for Hydrogen Atom in division Structure of Atom of Chemistry – Class 11

Answer 1

Correct answer is (d) 0.02645 nm

Easiest explanation: 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. For He^+, n = 1 and Z =2. Radius = 52.9(1)/2 pm = 0.02645 nm.