Final answer:
The second principal energy level of a hydrogen atom consists of two sublevels: 2s and 2p, which comprise of one and three orbitals respectively.
Step-by-step explanation:
The second principal energy level for the hydrogen atom contains two sublevels: the 2s and 2p. The n = 2 level can have sublevels with l values of 0 (2s) and 1 (2p). Therefore, there are two sublevels in the second principal energy level of a hydrogen atom. The 2s sublevel has one orbital, and the 2p sublevel consists of three orbitals, which are degenerate (having the same energy). The Aufbau principle and quantum mechanics help to understand this configuration, where electrons occupy orbitals from the lowest energy level to the highest.