Question

According to Bohr's theory, the radius of the $n^{th}$ orbit of an atom of atomic number Z is proportional to

• A. $\frac{n^2}{Z^2}$
• B. $\frac{n^2}{Z}$
• C. $\frac{n}{Z}$
• D. $n^2{Z}^2$

Answer 1

The correct option is B $\frac{n^2}{Z}$

According to Bohr's theory, $r_n=\left(\frac{{ϵ}_0{h}^2}{\pi m{e}^2}\right)\frac{n^2}{Z}=\frac{K{n}^2}{Z}$ where $K$ is a constant.
Hence, $r_n\propto \frac{n^2}{Z}$ and the correct choice is (b).