Question

helium atom has 2electrons in its valancy shell but its valancy is not 0 . explain​

Answer 1

Answer:

Helium atom has only one shell (K shell) which can have maximum 2 electrons. Thus, its shell is already complete called duplet. It can neither lose electrons nor gain electrons. Hence, its valency is 'zero'.

Answer 2

Answer:

because it has two electrons in last shell