The order of increasing energies of the various orbitals or electrons can be calculated on the basis of (n+1) rule. According to this rule, the lower the value of (n+1) for an orbital, lower is its energy. However, if the two different types of orbitals have the same values of (n+1), the orbital with lower value of n has lower energy. So, the order of energy, e3>e1>e2>e4