Question

The radius of electron's second stationary orbit in Bohr's atom is R. The radius of the third orbit will be.

• A. 3 R
• B. 2.25 R
• C. 9 R
• D. $\frac{R}{3}$

Answer 1

Answer: (B)

2.25 R

Answer 2

$r \propto n^{2}$ ⇒ $\frac{r_{(n = 2)}}{r_{(n = 3)}} = \frac{4}{9}$ ⇒ $r_{(n = 3)} = \frac{9}{4}R = 2.25R$