Given :            Fe+2 + 2e- ⇌ Fe E0 = – 0.44 V

                        Co+2 + 2e-⇌ Co E0 = – 0.28 V

                        Ca+2 + 2e- ⇌ Ca E0 = – 2.87 V

                        Cu+2 + 2e- ⇌ Cu E0 = + 0.337 V

Which is the most electropositive metal?

A galvanic cell is made up to SHE as cathode and another hydrogen electrode as anode. The other hydrogen electrode should be immersed in which of the following solutions to get maximum value of emf?

(a) 0.1 M HCl                         (b) 0.1 M CH₃COOH (K_a =10^-5)   

(c) 0.1 M H₂SO₄                     (d) 0.1 M H₃PO₄ (K_a1 = 10^-3)

Which of the following is/are functions(s) of salt bridge

A cell contains two hydrogen electrodes. The negative electrode is in contact of 10^-8 M hydrogen ions. The EMF of the cell is 0.236 V at 298 K. The concentration of hydrogen ions at the positive electrode is:

(a) 10^-6 M                 (b) 10^-4 M               (c) 10^-5 M              (d) 10^-3 M

For the electrode Pb (PbSO₄(s), SrSO₄(s) ) SrCl₂ (C molar), which of the following is correct representation of half cell reaction?

(a) Pb(s) + SrSO₄(s) ⇌ PhSO₄(s) + Sr²⁺ + 2e^–

(b) Pb(s) + SrCl₂ ⇌ PbCl₂ + Sr²⁺ + 2e^–

(c) Pb(s) + SrSO₄ + PbSO₄(s) ⇌ Pb²⁺ + Sr²⁺ + 2e^–

(d) None of the above reaction is correct representation

For the cell Ag(AgBr(s)) KBr (soln) ((Hg₂Br₂(s))Hg the measured e.m.f.s are 0.6839 v at 25^oC and 0.07048 V at 30^oC. What is the temperature coefficient of this cell?

(a) 4.2 x 10^-4 v/^oC           (b) 1.3 x 10^-5 v/^oC

(c) 2.1 x 10^-3 v/^oC           (d) 9.3 x 10^-3 v/^oC

This cell reaction will be spontaneous when

(a) p₁ = p₂ = 1 atm         (b) p₁ > p₂         

(c) p₁ < p₂                       (d)

Copper can be deposited from acidified CuSO₄ and alkaline CuCN. If 5 amp. Current is passed for 5 min through both the solutions separately, which of the following is correct.

Given electrode potentials are

Fe³⁺ + e → Fe²⁺ ; E⁰ = 0.771 V

I₂ + 2e → 2I^– ; E⁰ = 0.536 V

E⁰_cell for the cell reaction; 2Fe³⁺ + 2I^– → 2Fe²⁺ + I₂; is

(a) (2 x 0.771 – 0.536) = 1.006 V             (b) (0.771 – 0.5 x 0.536) = 0.503 V

(c) 0.771 – 0.536 = 0.235 V                      (d) 0.536 – 0.771 = -0.235 V

A hydrogen electrode placed in a buffer solution of CH₃COONa and acetic acid in the ratios x:y and y:x has electrode potential values E₁ volts and E₂ volts respectively at 25^oC. The pK_a values of acetic acid is (E₁ and E₂ are oxidation potential)

(a)                   (b) 

(c)                 (d) 

In an Electrolytic cell electrons flow from

Consider the following reactions:

Pb²⁺ _(aq) + 2e^– → Pb _(s)    E⁰ = -0.127 V

Cu⁺ _(aq) + e^– → Cu _(s)       E⁰ = +0.518 V

Which statement is true about a galvanic cell employing Pb, Cu, Pb²⁺ and Cu⁺?

Two platinum electrodes are dipped in a solution of HCl, and H₂ and Cl₂ gases are made to bubble through them at constant pressure. One half cell is Pt, H₂(g)|H₃O⁺ (aq) with reaction ½ H_­2 + H₂O → H₃O⁺ + e^–.

The electrode at which this half cell reaction would occur is

Cu⁺ + e^– → Cu, E⁰ = x₁V, Cu⁺² + 2e^– → Cu, E⁰ = x₂V

For Cu⁺² + e^– → Cu⁺, E⁰ will be

(a) x₁ – 2x₂                    (b) x₁ + 2x₂                   

(c) x₁ – x₂                       (d) 2x₂ – x­₁

Given E^o for Cu²⁺ → Cu⁺ is + 0.15 V and Cu⁺ → Cu is +0.50 V

Calculate E^o for Cu⁺² → Cu