The metal that cannot be obtained by the electrolysis of an aqueous solution of its salt is

Step-by-step solution

For the reduction of H 2 O at cathode, 2 H 2 O + 2 e - → H 2 g + 2 OH - ;   E red ∘ = - 1.23 V For Ca 2 + + 2 e - → Ca ;   E red ∘ = - 2.87 V i.e., water will be reduced at the cathode, in preference to the liberation of Ca . However, in the case of Ag ,   Cu   and   Cr , their standard reduction potentials are higher than - 1 . 23   V and will be liberated/ deposited at the cathode and H 2 O will not be reduced.