Which of the following elements exhibits the usual tendency to undergo reduction?

Identify the redox couples involved in the following reactions:
$(a) \ Cu + Zn^{+2} \to Cu^{+2} + Zn$
$(b) \ Mg + Fe^{+2} \to Mg^{+2} + Fe$
$(c) \ Br_{2} + 2Cl^{-} \to Cl_{2} + 2Br^{-}$
$(d) \ Fe + Cd^{+2} \to Cd + Fe^{+2}$

Which of the following phenomena represents oxidation?

Reduction involves

If an atom undergoes reduction,its oxidation number......

For the reaction $Ag_2O + H_2O + 2e^- \to 2Ag + 2OH^-$,which of the following is true?