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

The metal that cannot be obtained by the electrolysis of an aqueous solution of its salt is
  1. Ag
  2. Ca
  3. Cu
  4. Cr

Solution

For the reduction of H2O at cathode,

2H2O+2e-→H2g+2OH-; Ered∘=-1.23V

For Ca2++2e-→Ca; Ered∘=-2.87V

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 H2O will not be reduced.

Asked in: JEE Main 2014 (06 Apr)

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