00:02
Hi there.
00:03
In this question, we are given n equals three.
00:07
Well, n is the principal quantum number.
00:10
And what it tells us is the energy level.
00:15
Therefore, the energy level is three.
00:19
And we want to know how many sub -levels there are.
00:22
Well, what we know about quantum numbers is that the number, let me write that the other way.
00:33
The energy level is always equal to the number of sub -levels at that energy level.
00:51
In other words, when n equals one, when we're in the first energy level, there's only one sub -level, and that's an s.
00:57
When n equals two, there are two sub -levels being the s and the p.
01:03
When n -equals three, there are going to be three sub -levels.
01:10
Since our energy level is three, and the energy level is equal to the, the number of sub -levels, there will be three sub -levels...