Question

When hydrogen atom is in its first excited level, its radius, is

• A. twice
• B. half
• C. same
• D. four times

Answer 1

Answer: (D)

four times

Answer 2

We know that the radii of different orbits of the hydrogen atom are given by $r_{n}=n^{2} a_{0}$ where $a_{0}=$ radius of the ground state orbit $\therefore r_{n} \propto n^{2}$
$\therefore$ When the hydrogen atom is in first excited state (i.e., $n=2$ ), its radius is 4 times.