Aluminium displaces hydrogen from dilute HCl whereas silver does not. The e.m.f. of a cell prepared by combining `Al//Al^(3+)` and `Ag// Ag^(+)` is 2.46V. The reduction potential of silver electrode is +0.80V. The reduction potential of aluminium electrode is

Options

A. `+1.66V`
B. `-3.26V`
C. `3.26V`
D. `-1.66V`

Answer

D

Explanation

Al is more reactive than Ag, i.e., cell reaction is
`Al+3Ag^(+) to Al^(3+)+3Ag`
`E_(cell)=E_("cathode")^(@)-E_("anode")^(@)`
`=E_(Ag^(+)//Ag)^(@)-E_(Al^(3+)//Al)^(@)`
`2.46=0.80-E_(Al^(3+)//Al)^(@)`
or `E_(Al^(3+)//Al)^(@)=-1.66V`