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Question:

The electrons identified by quantum numbers n and l can be placed in the order of increasing energy as: 1. n=4, l=1 2. n=4, l=0 3. n=3, l=2 4. n=3, l=1

3>4<2<1

4<2<3<1

2<4<1≤3

1<3≤2<4

Solution:

The electrons are filled in the increasing order of (n+l) value.

  1. 4+1=5
  2. 4+0=4
  3. 3+2=5
  4. 3+1=4
    If (n+l) value is same for two different n and l value, then electron first fills in the orbital in which the n value is less.
    The correct order is 4<2<3<1.
    Hence, option B is correct.