Atomic Structure: Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Atomic Structure. Understanding the underlying formula is key to arriving at the correct answer below:

The radius of the nth Bohr orbit is given by $r_n = \frac{n^2 h^2 \epsilon_0}{\pi m Z e^2}$. This shows that the radius is directly proportional to the square of the principal quantum number, so $r \propto n^2$.