The electrons identified by quantum numbers n and l
1) n = 4, l = 1 2) n = 4, l = 0
3) n = 3, l = 2 4) n = 3, l = 1
can be placed in order of increasing energy as
a) c < d < b < a
b) d < b < c < a
c) b < d < a < c
d) a < c < b < d

Answer: b
Explanation: Greater the (n + l) value, greater is the energy. If (n + l) values are equal, then greater the ‘n’ value greater is the energy.