Which of the following options are correct for the reaction? 2 [Au...

Gold is then extracted from this complex by displacement technique by using a more electropositive zinc metal.

In this method, zinc ($Zn$) acts as a reducing agent and it reduces$Au{}^{+}$ to $Au$ and itself gets oxidized from $Zn$ to ${Zn}^{+ 2}$ ions which combine with ${CN}^{-}$ ions and form soluble complex, sodium tetracyanozincate (II).

$2{\left[Au ( CN{)}_{2}\right]}^{-}\left(aq\right) + Zn\left(s\right) \to 2Au\left(s\right) + {\left[Zn ( CN{)}_{4}\right]}^{2 -}\left(aq\right)$