Answer:
The splitting between energy levels is greater for higher lying energy levels than for lower lying energy levels because of the Coulomb force, which is the force of attraction or repulsion between charged particles.
In an atom, the positively charged nucleus exerts an attractive force on the negatively charged electrons, holding them in orbit around the nucleus. However, the electrons also repel each other due to their negative charges. The net result is that the energy levels of the electrons in an atom are determined by a balance between the attractive and repulsive forces acting on them.
The Coulomb force is proportional to the product of the charges of the interacting particles and inversely proportional to the square of the distance between them. As the distance between the nucleus and the electron increases, the Coulomb force becomes weaker, resulting in smaller energy differences between adjacent energy levels. Conversely, as the distance between the nucleus and the electron decreases, the Coulomb force becomes stronger, resulting in larger energy differences between adjacent energy levels.
Since higher lying energy levels are farther away from the nucleus than lower lying energy levels, the Coulomb force is weaker for the higher energy levels, resulting in larger energy differences between adjacent energy levels. This is why the splitting between energy levels is greater for higher lying energy levels than for lower lying energy levels.