Question

After filling 4s, the electron enter into which orbital

Answer 1

Answer:

The 4s sublevel is lower in energy, only if the 3d sublevel has no electrons. The 4s sublevel is filled before the 3d sublevel according to the Aufbau principle since the 4s are lower in energy. Hence the electron enter into 3d- orbit after filling up of 4s - orbital instead of 4p.

Answer 2

Answer:

after 4S the next one which the electron will enter is 3d because 3d has more (n+l) value than 4s