Question

The standard electrode potentials of $Zn$,
$Ag$ and $Cu$ are $- 0.76,0.80$ and $0.34$ volt respectively; then:
A. $Ag$ can oxidise $Zn$ and $Cu$
B. $Ag$ can reduce $Z{n^{2 + }}$ and $C{u^{2 + }}$
C. $Zn$ can reduce $A{g^ + }$ and $C{u^{2 + }}$
D. $Cu$ oxidise $Zn$ and $Ag$

Answer 1

The standard electrode potential of a certain species is a measure of the tendency for it to get reduced in a redox reaction, by accepting an electron. A more positive value of standard electrode potential means higher tendency to get reduced.

Complete step by step answer:
As we know, standard electrode potential is a measure of the tendency for it to get reduced in a redox reaction, by accepting an electron. So, elements with higher tendency to get reduced will have larger positive values of electrode potential. Comparing the electrode potentials of the elements given to us, we see that it lies in the order:
$Zn < Cu < Ag$
Thus, out of these three elements, silver has the highest tendency to get reduced while zinc has the least tendency. We know that oxidation and reduction are reverse processes of each other. That is, a reducing agent reduces other species by itself getting oxidised, and vice versa. In this series, as zinc has the lowest electrode potential, its tendency to get itself reduced is the least out of all three, implying that it can act as a good reducing agent (and thus, get itself oxidised). Hence, zinc can reduce silver and copper.
So, the correct option is C.

Note:
As silver has the highest electrode potential among these three, it has a high tendency to get reduced itself, and therefore, is unable to reduce zinc and copper.
Note that the oxidising/reducing ability of an ion/atom is dependent on how many electrons they need to remove/accept to acquire a fully filled outermost shell and thus, be stable.