The kinetic energy (KE) of an electron in a hydrogen atom depends on the energy level (n) it is in. Here is the formula for kinetic energy at level n : KEn=‌
13.6
n2
eV Step 1: Identify the energy levels The "third excited state" means n=4, and the "fourth excited state" means n=5. Step 2: Calculate the kinetic energy for n=4 KE3=‌
13.6
42
=‌
13.6
16
eV Step 3: Calculate the kinetic energy for n=5 KE4=‌