Question

why electrons enters into 4s but not 3d after completion of 3d explain​

Answer 1

Answer:

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Explanation:

Answer. Because according to Aufbau's principle,electrons get filled in the increasing level of energy of the orbitals,after 3p, among 4s(n+l=4) and 3d(n+l=5) energy of 4s is lower due to lower (n+l) value, therefore electrons tend to fill in the 4s orbital first.