Question

104, Lowest IP will be shown by the element having the
configuration :-
(1) [He] 2s2
(3) [He] 2s 2p2
(2) 152
(4) (He) 252 2p5​

Answer 1

Although Ne, He and N all have fully filled stable configuration but the electron is to be removed from a 1s shell in case of He. 1s shell being closest to the nucleus makes quite tough to remove an electron from it. Thus, the element having the highest I.P. value is Helium.