In Bohr's atomic model, the radius of the first orbit is $r_o$. The radius of the third orbit will be:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $9r_o$
Bohr's atomic model radius (r) is,
$r_n∝n^2$
$⇒r_n=r_on^2$ [$r_o$ = Bohr's atomic radius]
$⇒r_3(3)^2r_o=9r_o$