Question

what must done to a 2s electron to make it a 3s electron? what happens when a 3s electron becomes a 2s electron?

Answer 1

You must give energy to the electron. It will get excited and jump to outer shell. Due to excess energy it will release energy and emit radiations to return back to ground state

Answer 2

when energy is given to 2s electron then it get energy and become excited and go to 3s while when it have excess energy it release energy and comes to 2s