Posted by Kamila on Monday, April 18, 2011 at 7:53pm.
Hint:
For n=5, l can be 0, 1, 2,3, and 4.
For 1=1 you know ml can be -1,0,+1 so for
2, 3, and 4, there must be how many -2s for mL. And if you can put two electrons into each of those orbitals, how many total is that?