Question

How is the valency and electron transfer related in this case ?​

Answer 1

Electron transfer (ET) occurs when an electron relocates from an atom or molecule to another such chemical entity. ET is a mechanistic description of a redox reaction, wherein the oxidation state of reactant and product changes.

Answer 2

Valency and electron transfer are same in this case as both valency and numbered of electrons transfered or received is 2.