11th class - Arrangement of Orbitals with Increasing Energy on the Basis of (n+l) Rule

Orbital	Value  of n	Value of l	Value of  (n+l)
1s	1	0	1+0=1
2s	2	0	2+0=2
2p	2	1	2+1=3	2p (n=2) has lower energy than
3s	3	0	3+0=3	3s (n=3)
3p	3	1	3+1=4	3p (n = 3) has lower energy than
4s	4	0	4+0=4	4s (n = 4)
3d	3	2	3+2=5	3d (n = 3) has lower energy than
4p	4	1	4+1=5	4p (n=4)