ElectroChemistry : Important Multiple Choice Questions And Answers

List of Questions and Answers

1.A solution of copper sulphate is to be stored in a container made of a metal. Which of the following metals is/are suitable for this purpose?
(i) silver
(ii) lead
(iii) zinc
(The standard electrode potentials for Cu2+, Ag+, Pb2+ and Zn2+ are 0.34V, 0.80V, -0.13V and -0.76V, respectively.)
(A) (i) only
(B) (ii) and (iii)
(C) (i) and (ii)
(D) (i) ,(ii) and (iii)

Ans: (A) (i) only

2.The reaction Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s) at 300 K has Eocell = 1.2V.
The equilibrium constant for this reaction is (2.303 RT/F = 0.06V)
(A) 40
(B) 1010
(C) 1020
(D) 1040

Ans: (D) 1040

3.The potential of hydrogen electrode corresponding to the reaction
H+(aq) + e- → ½ H2(g) in contact with a solution of pH = 9 is
(given the pressure of H2 gas is 1 bar and 2.303 RT/F = 0.06 V)
The equilibrium constant for this reaction is (2.303 RT/F = 0.06V)
(A) -0.54 V
(B) 0 V
(C) 0.27 V
(D) 1.08 V

Ans: (A) -0.54 V

4.If the distance between Na+ and Cl- ions in sodium chloride crystal is X pm, the length of the edge of the unit cell is:
(A) X/2 pm
(B) 2X pm
(C) 4X pm
(D) X/4 pm

Ans: (B) 2X pm

5.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 2.46 V.The reduction potential of silver electrode is +0.80V.The reduction potential of aluminium electrode is:
(A) 3.26 V
(B) -1.66 V
(C) +1.66 V
(D) -3.26 V

Ans: (B) -1.66 V

6.The hydrogen electrode is dipped in a solution of pH 3 at 25oC .The potential would be (the value of 2.303 RT/F is 0.059 V)
(A) 0.177 V
(B) 0.087 V
(C) 0.059 V
(D) -0.177V

Ans: (B) 0.087 V

7. How long it will take for the deposition of 0.2g of silver when silver nitrate solution is electrolysed using 0.5 ampere of current (Mol mass of Ag = 108)
(A) 357.4 seconds
(B) 234.4 seconds
(C) 120 seconds
(D) 180.5 seconds

Ans: (A) 357.4 seconds

8.Given : EoMn+7|Mn+2 = 1.5 V and EoMn+4|Mn+2 = 1.2 V , then EoMn+7|Mn+4 is
(A) 0.3 V
(B) 1.7 V
(C) 0.1 V
(D) 2.1 V

Ans: (B) 1.7 V

9.For a cell reaction involving two electron changes, Eocell = 0.3 V at 25oC . The equilibrium constant of the reaction is :
(A) 10-10
(B) 3 x 10-2
(C) 10
(D) 1010

Ans: (D) 1010

10.The products of hydrogen fuel cell are:
(A) smoke and carbon dioxide
(B) hydrogen and oxygen
(C) hydrogen and electricity
(D) water and electricity

Ans: (D) water and electricity

11.The electrical resistance of a column of 0.1 mol L-1 KOH solution of area 10 cm2 and length 50cm is 5 x 103 Ω.The molar conductivity of the solution is :
(A) 0.01 S cm2 mol-1
(B) 0.1 S cm2 mol-1
(C) 5 S cm2 mol-1
(D) 10 S cm2 mol-1

Ans: (D) 10 S cm2 mol-1