Question

please give me answer quickly

Answer 1

hii frnd

here is ur answer
due to aufbau principle3d^3come first than 4s^2.....

thnku

hope it's help u! ! !

Answer 2

When we write the electronic configuration we write the energy level having lower principle value first and then higher but we fill the lower energy level first.
3d has lower principle quantum number value (n) than 4s so we write 3d before 4s but we fill 4s first and then 3d.
This is the way how you write and how you should write in boards.