GENERAL KNOWLEDGE

Detailed explanation-1: -Valence electrons are the electrons in the outermost shell, or energy level, of an atom. For example, oxygen has six valence electrons, two in the 2s subshell and four in the 2p subshell. We can write the configuration of oxygen’s valence electrons as 2s²2p⁴.

Detailed explanation-2: -Valency depends on the number of electrons in the outermost shell (i.e. valence shell). If the number of electrons present in the outermost shell are 1, 2, 3, or 4, then their valency is 1, 2, 3 or 4 respectively.