How many energy sublevels correspond to hydrogen's first three energy levels?

The first three energy levels of hydrogen correspond to specific principal quantum numbers, which are denoted as n=1, n=2, and n=3. Each principal energy level can have a certain number of sublevels, which are determined by the value of n.

For the first energy level (n=1), there is only one sublevel, which is the 1s sublevel. For the second energy level (n=2), there are two sublevels: the 2s and 2p sublevels. For the third energy level (n=3), there are three sublevels: the 3s, 3p, and 3d sublevels.

Thus, the total number of energy sublevels corresponding to the first three energy levels is 1 for n=1, 2 for n=2, and 3 for n=3, aligning perfectly with the choice that lists 1, 2, and 3. This reflects the fundamental structure of atomic energy levels in quantum mechanics, where the number of sublevels corresponds directly to the principal quantum number.