Aluminium displace hydrogen from dilute HCl where as silver does not. The E.M.F of a cell prepared by combining Al/Al+3 and Ag/Ag+ is 2.46 V. The reduction potential of silver electrode is + 0.81 V. The reduction potential of aluminium electron is:
3.26 V
-1.66 V
+1.66 V
-3.26 V