The radius of first Bohr’s orbit for hydrogen is 0.53 A°. The radius of third Bohr’s orbit would be

The radius of first Bohr’s orbit for hydrogen is 0.53 A°

The radius of 3^rd Bohr’s orbit for hydrogen is 0.529 $\times$n² /Z

 (r) = 0.529$\times$3² /1

 (r) =4.761 A⁰