Worksheet based on Electro-Chemistry





The study of chemical reaction that takes place in a solution with the interface of an electron conductor and ionic conductor is known as Electro-chemistry.

Here, you can find some questions related to “Electro-chemistry” and their answers:

Questions:

1. During the electrolysis of aqueous nitric acid solution using Pt electrodes:

(a)    N_2 is liberated at the anode

(b)   H_2 is liberated at the anode

(c)    O_2 is liberated at the anode

(d)   O_2 is liberated at the cathode

 

2. During the electrolysis ofCa(NO_3);

(a)    Nitrogen gas is evolved at the cathode

(b)   Calcium deposits at the anode

(c)    Calcium deposits at the cathode

(d)   Oxygen gas is evolved at the anode

 

3. How many Faradays are required to reduce one mole of Cr_2O^{2-}_7 to Cr^{3+}?

(a)    12

(b)   6

(c)    9

(d)   4

 

4. The function of a salt bridge is to:

(a)    Eliminate liquid-junction potential where the ions are present in large excess at the junction

(b)   Decrease the cell potential at the negative electrode

(c)    Eliminate the impurities present in the electrolyte

(d)   Increase the cell potential at the positive electrode

 

5. The potential difference of the Weston cell at 25° C is:

(a)    1.018 V

(b)   2.045

(c)    1.500 V

(d)   0.1018

 

6. KCI can not be used as a salt bridge for the cell Cu(s) | CuSO_4 (aq) || AgNO_3 (aq) || Ag(s) because:

(a)    Cl_2 gas a evolved

(b)   CuCl_2 gets

(c)    AgCl gets

(d)   None of the above – )

 

7. Which of the following statements is correct in the contest of a battery ?

(a)    The stored energy is released during the redo reaction.

(b)   It is an electrochemical cell

(c)    It is used as a source of energy

(d)   All of these

 

8. Which of the following equations is correct in the context of Kohlrausch’s law?

(a)    \Lambda = \Lambda^0- B\sqrt{C}

(b)   \Lambda = \Lambda^0 + BC^{1/2}

(c)    \Lambda^0 = \Lambda- B \sqrt{C}

(d)   \Lambda = \Lambda^0- BC

 

9. Indicate the correct expression:

(a)    K = c(\lambda^-_+ + \lambda^0_-)

(b)   C = K(\lambda^0_+ + \lambda^0_-)

(c)    C = C \lambda^0_+ + \lambda^0_-

(d)   K = \sqrt{C}(\lambda^0_+ + \lambda^0_-)

 

10. The units of ionic mobility are:

(a)    Cm^{S-1}V^{-1}

(b)   cm^{-2}S^{-1}V^{-2}

(c)    cm^2S^{-1}V^{-1}

(d)   cm^2S^{-1}V^{-2}

 

11. The hydrogen electrode is dipped in a solution of P^H at 25° C The potential of the cell would be (the value of 2.303 RT/F is 0.059 V).

(a)    0.1-77V

(b)   0.

(c)    -0.

(d)   0.087V

 

12. Depolariser used in cells is:

(a)    MnO_2

(b)   ZnCl_2

(c)     Carbon

(d)   NH_4Cl

 

13. Which is an example of corrosion:

(a)    Tarnishing of silver

(b)   Rusting of iron

(c)    Development of a green coating on

(d)   All.

 

14. KCl can not be used in salt bridge for the cell Ag | Ag^+ || Fe^{3+}|Fe  it is because:

(a)    Cl_2 gas is evolved

(b)   FeCl_3 gets hydrolysed

(c)    AgCl gets precipitated

(d)   None of the above

 

15. In the electroplating of nickel over an article made of iron, the electrolyte generally used is:

(a)    FeSO_4

(b)   NiSO_4

(c)    NiSO_4(NH_4)_2SO_4

(d)   May be NiSO_4 or FeSO_4

 

16. At what value of cell constant, the specific conductance and conductance of a solution is same:

(a)    Ten

(b)   One

(c)    Hundred

(d)   Zero

 

17. If a strip of copper metal be dipped in a solution of ferrous sulphate:

(a)    Copper and iron both will be dissolved

(b)   Copper will precipitate out

(c)    Iron will precipitate out

(d)   No reaction will occur.

 

18. In the reaction:

Cu(s) + 2Ag^+(aq) \to Cu^{++}(aq) + 2Ag(s):

(a)    Cu(s) is oxidised to Cu^{2+}(aq)

(b)   Ag^+(aq) is oxidised to Ag(s)

(c)    Both Cu(s) and Ag^+(aq) are oxidised

(d)   Cu(s) is reduced to Cu^{2+}(aq)

 

19. The correct way to representing Daniel cell is:

(a)    Zn | Zn^{++} || Ag^+ | Ag

(b)   Zn | Zn^{++} || Cu^{++} | Cu

(c)    Pt, H_2 | H^+ || Hg^{++} | Hg

(d)   Cu | Cu^{++} || H^+ | H_2, Pt

 

20. Point out the incorrect statement:

(a)    Standard electrode potential electrode is zero

(b)   An electrochemical cell is a device which converts chemical energy into electrical energy

(c)    A salt bridge is used to eliminate liquid junction potential  of hydrogen

(d)   Calomel electrode is not used as a reference electrode

 

21. From the half cell potential values,

 E^0 Cu | Cu^{++} = -0.337 Volt;

E^0 Ag / Ag^+ = -0.118 Volt  the emf of the cell,

Cu| CU^{++} || Ag^+ | Ag will be:

(a)    +1.136 Volt

(b)   +0.462 Volt

(c)    -1.136 Volt

(d)   -0.462 Volt

 

22. In electrochemical series, are placed:

(a)    Only non-metal elements

(b)   Only metal elements

(c)    Both metal and non-metal

(d)   Metals & hydrogen

 

23. Among F^-, Cl^-, I^- bromine can oxidise:

(a)    I^-

(b)   Cl^-

(c)    F^-

(d)   All of these

 

24. An apparatus used for the measurement of quantity of electricity is known as:

(a)    Calorimeter

(b)   Cathetometer

(c)    coulometer

(d)   Colorimeter

 

25. 1 Faraday of electricity will give 1 gm atom from which of the solution:

(a)    NaCl

(b)   CuSO_4

(c)    MgCl_2

(d)   AlCl_3

 

Answers:

1.(c)     2. (d)     3. (b)     4. (a)     5. (a)

6. (c)     7. (d)     8. (a)    9. (a)     10. (c)

11. (a)     12. (a)     13. (d)     14. (c)     15. (c)

16. (b)     17. (d)     18. (a)     19. (b)     20. (d)

21. (b)     22. (c)     23. (a)     24. (c)     25. (a)



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