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 for a hydrogen atom is $r_n = a_0 n^2$. For the second orbit ($n=2$), the radius is $r_2 = a_0 (2^2) = 4a_0$.