How can an atom achieve octet?

What is valency of an atom? Explain how an atom can achieve an octet in their outermost shell and also explain how an atom can be chemically stable.

Assertion :- CH_4 obeys the octet rule. Reason :- During the formation of CH_4 molecules, carbon atom achieves an octet.

Assertion : In the formation of a molecule , only the outer shell electrons take part in chemical combination and they are known as valence electrons. Reason : Atoms achieve the stable octet when they are linked by chemical bonds .

Assertion : In the formation of a molecule , only the outer shell electrons take part in chemical combination and they are known as valence electrons. Reason : Atoms achieve the stable octet when they are linked by chemical bonds .

An atom can achieve octet by ……………..or ………………of electrons.

How can we achieve this (convertion of electrical energy to mechanical energy)?