Question

Please help me Q5(a)(b) but the answer should be very short

Answer 1

Valence electrons are the number of electrons in the last shell of an atom.

Valency is the number of atoms gained or lost by an atom in order to become stable by attaining the electronic configuration of the nearest noble.

Variable Valency is a phenomenon usually found in transition elements of the modern periodic table. It occurs as the second last shell of these elements is not completely filled with electrons. Variable Valency is exhibited by metals like iron :fe2+fe3
copper:cu2+cu3

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Answer 2

Hope it help you bhanji