Electrons will first enter into the set of quantum numbers n=5, l=0 or

1.	Electrons will first enter into the set of quantum numbers n=5, l=0 or n=3 , l=2
Answer» n=5, l=0 Both possible n=3, l=2 DATA insufficient Solution :According to AUFBAU's priciple, electron enter in the orbitals according to their ENERGY. Energy of an orbital is proportional to the SUN (n+l). If the two orbitals (n+l) is equal then electron will be filled in the orbital having lesser value of n. HENCE, here electron will be filled in the orbital with n=3, l=2

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