Each of the following redox reaction occurs spontaneously.
`Mg(s)+Zn^(2+)(aq)rarrZn(s)+Mg^(2+)(aq)`
`Cu(s) + 2Ag^+(aq) rarr 2Ag(s) + Cu^(2+)(aq)`
Arrange, with explanation, Mg, Zn, Cu and Ag in order of their decreasing standard reduction potentials.

Explanation

Mg is oxidised and `Zn^(2+)` is reduced Hence, `E_(Mg^(2+)|Mg)^(@) lt E_(Zn^(2+)|Zn)^(@)`.
Therefore the decreasing order of the standard reduction potential of the given systems are :
`E_(Mg^(2+)|Mg)^(@)lt E_(Zn^(2+)|Zn)^(@) lt E_(Cu^(2+)|Cu)^(@)ltE_(Ag^(+)|Ag)^(@)`