MCQ Questions for Class 12 Chemistry Chapter 3 Electrochemistry with Answers
CBSE: NCERT Solutions for Class 12 Chemistry Chapter 3 Electrochemistry MCQ’s with Answers
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NCERT Physics MCQs for Class 12 Chemistry Chapter 3 Electrochemistry Answers and Questions PDF
Q1. Standard solution of KNO3 is used to make a salt bridge because
(a) Velocity of K+ is greater than that of NO.
(b) Velocity of NO is greater than that of K+.
(c) Velocity of both K+ and NO are nearly same
(d) KNO3 is highly soluble in water.
Answer:(c) Velocity of both K+ and NO are nearly same
Q2. Galvanised iron sheets are coated with
Q3. How many coulombs are required for the oxidation of 1 mole of H2O to O2?
(a) 1.93 × 105 C
(b) 9.65 × 104 C
(c) 3.86 × 105 C
(d) 4.825 × 105 C
Answer:(a) 1.93 × 105 C
Q4. Rust is a mixture of
(a) FeO and Fe (OH)3
(b) FeO and Fe (OH)2
(c) Fe2O3 and Fe (OH)3
(d) Fe3O4 and Fe (OH)3
Answer:(c) Fe2O3 and Fe (OH)3
Q5. The Standard electrode potentials for the half cell reactions are as follows Zn ? Zn2+ + 2e– [E° = 0.41 V] Fe ? Fe2+ + 2e– [E° = 0.76 V]
(a) -0.35 V
(b) 0.35 V
(c) + 1.17 V
(d) -1.17 V
Answer:(b) 0.35 V
Q6. The standard reduction potentials of Cu2+/Cu and Cu2+/Cu+ are 0.337 and 0.153 respectively. The standard electrode potential of Cu+/Cu half cell is
(a) 0.184 V
(b) 0.827 V
(d) 0.490 V
Q7. The standard reduction potentials of X, Y, Z metals are 0.52, -3.03, -1.18 respectively. The order of reducing power of the corresponding metals is:
(a) Y > Z > X
(b) X > Y > Z
(c) Z > Y > X
(d) Z > X > Y
Answer:(a) Y > Z > X
Q8.Which of the following is not a good conductor?
(a) Cu (b) NaCl (aq)
(c) NaCl (molten) (d) NaCl(s)
Q9.The volume of H2 gas at NTP obtained by passing 4 amperes through acidified H+O for 30 minutes is:
(a) 0.0836 L (b) 0.0432 L
(c) 0.1672 L (d) 0.836 L
Answer:(a) 0.0836 L
Q10. 4.5 g of aluminium (at. mass 27 amu) is deposited at cathode from Al3+ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H+ ions in solution by the same quantity of electric charge will be:
(a) 44.8 L (b) 11.2 L (c) 22.4 L (d) 5.6 L
Answer:(a) 44.8 L
Q11. The amount of electricity required to deposit 1 mol of aluminium from a solution of AlCl3 will be
(a) 0.33 F (b) 1 F (c) 3 F (d) 1 ampere
Answer:(c) 3 F
Q12. A current of 2.0 A passed for 5 hours through a molten metal salt deposits 22.2 g of metal (at. wt. = 177). The oxidation state of the metal in the metal salt is
(a) +1 (b) +2 (c) +3 (d) +4
Q13. Standard electrode potentials are Fe2+/Fe, E° = – 0.44; Fe3+/Fe2+, E° = 0.77 V. Fe2+, Fe3+ and Fe blocks are kept together then
(a) Fe3+ increases (b) Fe3+ decreases
(c) Fe2+/Fe3+ remains unchanged (d) Fe2+ decreases?
Answer:(b) Fe3+ decreases
Q14. On the basis of information available from the reaction. 4/3 Al + O2 ? 2/3 Al2O3, ?G = – 827 kj mol-1 of O2 the minimum emf required to carry out the electrolysis of Al2O3 is
(a) 2.14 V (b) 4.28 V
(c) 6.42V (d) 8.56V
Answer:(a) 2.14 V
Q15. For a cell reaction involving two electron change the standard emf of the cell is found to be 0.295 V at 25°C. The equilibrium constant for the reaction at 25°C will be:
(a) 2.95 × 10² (b) 10
(c) 1 × 1010 (d) 1 × 10-10
Answer:(c) 1 × 1010
Q16. If Zn2+/Zn electrode is diluted 100 times, then the change in emf is
(a) increase of 59 mV (b) decrease of 59 mV
(c) increase of 29.5 mV (d) decrease of 29.5 mV.
Answer:(b) decrease of 59 mV
Q17. If the equivalent conductance of 1 M benzoic acid is 12.8 ohm-1 cm² and if the conductance of benzoate ion and H+ ion are 42 and 288.42 ohm-1 cm² respectively, its degree of dissociation is:
(a) 39% (b) 3.9% (c) 0.35% (d) 0.039%
Q18. The highest electrical conductivity of the following aqueous solutions is of?
(a) 0.1 M acetic acid (b) 0.1 M chloro acetic acid
(c) 0.1 M fluoroacetic acid (d) 0.1 M difluoro acetic acid
Answer:(d) 0.1 M difluoro acetic acid
Q19. If the conductivity and conductance of a solution is same then its cell constant is equal to:
(a) 1 (b) 0 (c) 10 (d) 1000
Q20. The resistance of 0.1 N solution of acetic acid is 250 ohm, when measured in a cell of cell constant 1.15 cm-1. The equivalent conductance (in ohm-1 cm² equivalent-1) of 0.1 N acetic acid is
(a) 18.4 (b) 0.023 (c) 46 (d) 9.2
Q21. The limiting molar conductivities A° for NaCl, KBr and KCl are 126, 152 and 150 S cm² mol-1 respectively. The A° for NaBr is
(a) 278 S cm² mol-1 (b) 976 S cm² mol-1
(c) 128 S cm² mol-1 (d) 302 S cm² mol-1
Answer:(c) 128 S cm² mol-1
Q22. The ionisation constant of a weak electrolyte is 2.5 × 10-5 and molar conductance of its 0.01 M solution is 19.6 S cm² mol-1. The molar conductance at infinite dilution (S cm² mol-1) is
(a) 402 (b) 392 (c) 306 (d) 39.2
Q23. Which of the following statements is incorrect about electrochemical cell?
(a) Electrons are released at anode.
(b) Chemical energy is converted into electrical energy.
(c) Salt bridge maintains the electrical neutrality of the electrolytes.
(d) Cell can work indefinitely.
Answer:(d) Cell can work indefinitely.
Q24. Point out the correct statement in a cell of zinc and copper:
(a) Zinc acts as cathode and copper as anode.
(b) Zinc acts as anode and copper as cathode.
(c) The standard reduction potential of zinc is more than that of copper.
(d) The flow of electrons is from copper to zinc.
Answer:(b) Zinc acts as anode and copper as cathode.
Q25. A zinc electrode is placed in 0.1 M solution of ZnSO4 at 25°C. Assuming that the salt is dissociated to an extent of 20% at this dilution, the potential of this electrode is (E° = -0.76V)
(a) – 0.81 V (b) – 0.79 V
(c) 0.81 V (d) 0.79 V
Answer:(a) – 0.81 V
Q26.E°cell apd ΔG° are related as:
(a) ΔG° = nF E°cell (b) ΔG = -nF E°cell
(c) ΔG° = -nF E°cell (d) ΔG° = nF E°cell = 0.
Answer: (c) ΔG° = -nF E°cell
Q27.Which of the following will decrease the voltage of the cell?
Sn(s) + 2Ag+ (aq) → Sn2+ (aq) + 2 Ag(s)
(a) increase in the size of silver rod
(b) increase in the concentration of Sn2+ ions
(c) increase in the concentration of Ag+ ions
(d) None of the above.
Answer: (b) increase in the concentration of Sn2+ ions
Q28.By how much will the potential of a zinc electrode change if the solution of ZnSO4 in which it is immersed is diluted to 10 times at 298 K?
(a) Decreases by 30 mV
(b) Increases by 30 mV
(c) Increases by 60 mV
(d) Decreases by 60 mV
Answer: (b) Increases by 30 mV
Q 29.The e.m.f. of the cell: Cu(s) | Cu2+ (1M) | | Ag+ (1M) | Ag is 0.46 V. The standard reduction potential of Ag+|Ag is 0.80 V. The standard reduction potential of Cu2+ |Cu is
(a) -0.34 V (b) 1.26 V (c) -1.26 V (d) 0.34 V
Answer: (d) 0.34 V
Q30.Saturated solution of KNO3 is used to make salt bridge because
(a) velocity of K+ is greater than that of NO
(b) velocity of NO is greater than that of K+
(c) velocity of both K+ and NO are nearly the same
(d) KNO3 is highly soluble in water.
Answer: (c) velocity of both K+ and NO are nearly the same
We hope that the given NCERT MCQ Questions for Class 12 Chemistry with Answers MCQ Chapter 3 Electrochemistry Free Pdf download will help you in gaining knowledge on the subject.