Top practice question on Electrochemistry:-

1) The charge required for reduction of 1 mole of MnO4-  ions into Mn2+  ions is-

            (a) F        (b) 3F           (c) 6F        (d) 5F

ANS:- (d) 5F

2) The pH of  0.5L of 1.0 M  NaCl after the electrolysis for 965 s using 5.0A current is-

                     (a) 1.0                            (b) 12.7      

                     (c) 13.0                          (d) 1.30

ANS:-  (c) 13.0     

3) The standard reduction potentials for metals P,Q,R and S are respectively +0.34V,   -0.762V, -3.05V, and +0.80V .Which one is strongest reducing agent?

            

           a) P       (b) S        (c) R        (d) Q

ANS:-(c) R  

4) How much electric charge is required to oxidise 1 mole of H2O to O2?

                (a) 193000C             (b) 96500C       

                (c) 18500C               (d) 48250C

ANS:-(a)193000C

5) A current of 0.20A is passed for 482 Sec through 50ml of 0.1M NaCl. What will be     the hydroxide ion Concentration in the Solution after the electrolysis?

                    

              (a) 0.0159M                    (b) 0.0199M

             (c) 0.10M                        (d) 0.030M

ANS:- (b) 0.0199

6) The number of faradays required to deposit one mole of atoms of metal M at the       cathode when a solution of its ions Mn+ is electrolysed is-

               (a) 1/n            (b) 1        (c) n      (d) None

ANS:-(c) n 

7) If Murcury is used as cathode in the electrolysis of aqueous NaCl solution , the ion   discharged at cathode is-

    

    (a) H+        (b) Na+        (c) OH-        (d) Cl-

ANS:-(b) Na+   

8) The amount of an ion discharged during electrolysis is not depends of-

  

   (a) resistance of solution

   (b) time

   (c) current strength

   (d) electrochemical equivalent of the element

ANS:-(a) resistance of solution

9) Which of the following solution will have the highest conductivity?

    (a) 0.1M CH3COOH                        

    (b) 0.1M NaCl.

    (c) 0.1M HCl                                   

   (d) 0.1M NH4OH

ANS:-(c) 0.1M HCl   

10) Calculate the potential of hydrogen electrode in contact with a solution whose pH   is 10----

          (a) -0.72V                               (b) -0.59V    

          (c) +0.59V                              (d) -0.51V

 Ans:-(b) -0.59V