Question

when a non metal gains or shares by two electrons,its valency will be​

Answer 1

When a non metal gains or share by two electrons then the valency will be 2^- or 2^+

Answer 2

As electrons are negatively charged particles, if it loses 2 electrons, there will be more protons than electrons by 2, therefore the valency will be 2+. If it gains 2 electrons, there will be more electrons than protons by 2, therefore the valency in this case will be 2-.