Correct Answer -
Copper can be extracted by hydrometallury but
not zinc , this is becomes ` E_(2n^(2+)//Zn)^(@) =- 0.76 V` is
lower than that `E_(Cu^(2+)//Cu)^(@)=0.34 V ` Hence , zinc
can displace Cu from solutions of `Cu^(2+)` ions .
`Zn (S) +Cu^(2+) (aq) to An^(2+)(aq) +Cu(s)`
In order to distance zinc solution , a
more reactiv metal is required , such as
`Al(E_(Al^(3+)//Al)^(@) =-1.66 V), Mg (E_(mg^(2+)^(@)=-2.37 V), `
`Ca (E_(Ca^(2+)//Ca)^(@) =-2.87 V),K (E_(K^(+)//K)^(@) =--2.93 V).`
But with water metals `(Al,Mg .Ca and K) forms their corresponding ions with the evolution of `H_(2)` gas . thus ,Al Mg ,Ca ,K etc. cannot be used to distance zinc from zinc solution and only copper can be extracted by hydrometallurgy but not the zinc .
