Question

Objective Ap-block element in which last electron enters into s-orbital of valence shell instead of p-orbital 15 (a) As (b) Ga c) He (d) No such element exist​

Answer 1

Answer:

Electronic configuration of He is 1s

2

. It is kept in p-block with group 18 elements even after last electron enters into s-orbital of valence shell instead of p-orbital because it is a noble metal.

Answer 2

Answer:

(c) He

The electronic configuration of helium is 1s²

The position of helium in periodic table is in p-block and group 18 because it is noble gas.

Helium also possess a completely filled electronic configuration like other inert gases. For all such reasons Helium is placed in inert gases group which lies in p block.