JEE Main - Electrochemical cells electrode potentials Nernst equation and fuel cells Online Test (MCQ Quiz)

1. What is the primary function of an electrochemical cell?

A) To generate electrical energy from chemical reactions B) To use electrical energy to drive non-spontaneous chemical reactions C) To measure the rate of chemical reactions D) To determine the equilibrium constant of reactions

2. In an electrochemical cell, which electrode is the site of oxidation?

A) Cathode B) Anode C) Salt bridge D) Electrolyte

3. Reduction occurs at which electrode in an electrochemical cell?

A) Anode B) Cathode C) Working electrode D) Reference electrode

4. What is the standard electrode potential (E°)?

A) The potential of an electrode at any concentration and temperature B) The potential of an electrode at 25°C and 1 atm pressure C) The potential of an electrode at standard conditions (298 K, 1 atm, 1 M concentration) D) The potential difference between two electrodes at equilibrium

5. Which of the following statements is true for a spontaneous redox reaction in an electrochemical cell?

A) The cell potential (E_cell) is negative B) The Gibbs free energy change (ΔG) is positive C) The cell potential (E_cell) is positive D) The reaction quotient (Q) is equal to the equilibrium constant (K)

6. The Nernst equation relates the electrode potential to:

A) Temperature and pressure only B) Concentration of reactants and products C) Standard electrode potential and reaction quotient D) The number of electrons transferred and the Faraday constant

7. What is the Nernst equation for a single electrode at 298 K?

A) E = E° - (RT/nF) ln Q B) E = E° + (RT/nF) ln Q C) E = E° - (2.303RT/nF) log Q D) E = E° + (2.303RT/nF) log Q

8. At 298 K, the Nernst equation can be simplified to:

A) E = E° - (0.0591/n) log Q B) E = E° + (0.0591/n) log Q C) E = E° - (0.0591/n) ln Q D) E = E° + (0.0591/n) ln Q

9. What does 'n' represent in the Nernst equation?

A) The number of moles of reactants B) The number of moles of products C) The number of electrons transferred in the redox reaction D) The number of half-cells in the electrochemical cell

10. If the concentration of products is higher than reactants (Q > 1), the electrode potential (E) will:

A) Increase B) Decrease C) Remain the same D) Become zero

11. What is the relationship between the cell potential (E_cell) and the standard cell potential (E°_cell) at non-standard conditions?

A) E_cell = E°_cell - (RT/nF) ln Q B) E_cell = E°_cell + (RT/nF) ln Q C) E_cell = E°_cell - (2.303RT/nF) log Q D) E_cell = E°_cell + (2.303RT/nF) log Q

12. A fuel cell is a type of electrochemical cell that:

A) Stores electrical energy B) Converts chemical energy from a fuel into electrical energy C) Uses electrical energy to produce fuel D) Generates heat rather than electricity

13. Which of the following is a common fuel used in fuel cells?

A) Methane B) Hydrogen C) Propane D) Butane

14. In a hydrogen-oxygen fuel cell, what is the overall reaction?

A) 2H₂ + O₂ → 2H₂O B) H₂ + O₂ → H₂O₂ C) 2H₂O → 2H₂ + O₂ D) H₂O₂ → H₂O + ½O₂

15. What is the main advantage of using fuel cells over conventional combustion engines?

A) Higher cost of production B) Lower efficiency C) Reduced pollution and higher efficiency D) Limited lifespan

16. Which species is oxidized at the anode of a hydrogen-oxygen fuel cell?

A) O₂ B) H₂O C) H₂ D) OH⁻

17. Which species is reduced at the cathode of a hydrogen-oxygen fuel cell (alkaline electrolyte)?

A) H₂ B) O₂ C) H₂O D) H⁺

18. The electromotive force (EMF) of a fuel cell is generally:

A) Independent of the fuel and oxidant B) Dependent on the type of fuel and oxidant C) Always 1.1 V D) Zero at standard conditions

19. What is the standard electrode potential for the reduction of H⁺ to H₂ (SHE - Standard Hydrogen Electrode)?

A) 1.00 V B) -0.00 V C) 0.00 V D) 0.50 V

20. If a half-reaction has a standard reduction potential of +0.80 V, it is more likely to be reduced than a half-reaction with a standard reduction potential of:

A) +1.20 V B) +0.34 V C) +0.80 V D) +0.90 V

21. Which of the following is a characteristic of a galvanic cell?

A) It uses electrical energy to drive a non-spontaneous reaction. B) It converts chemical energy into electrical energy. C) The anode is the site of reduction. D) The cathode is the site of oxidation.

22. What is the purpose of the salt bridge in a galvanic cell?

A) To increase the voltage B) To provide a path for electron flow C) To complete the internal circuit by allowing ion migration D) To act as the site of oxidation

23. Consider the Daniell cell: Zn(s) | Zn²⁺(aq) || Cu²⁺(aq) | Cu(s). What is the anode reaction?

A) Zn²⁺(aq) + 2e⁻ → Zn(s) B) Cu²⁺(aq) + 2e⁻ → Cu(s) C) Zn(s) → Zn²⁺(aq) + 2e⁻ D) Cu(s) → Cu²⁺(aq) + 2e⁻

24. In the Daniell cell (Zn | Zn²⁺ || Cu²⁺ | Cu), what is the cathode reaction?

A) Zn(s) → Zn²⁺(aq) + 2e⁻ B) Cu²⁺(aq) + 2e⁻ → Cu(s) C) Zn²⁺(aq) + 2e⁻ → Zn(s) D) Cu(s) → Cu²⁺(aq) + 2e⁻

25. The standard cell potential (E°_cell) of a galvanic cell is calculated as:

A) E°_cathode - E°_anode B) E°_anode - E°_cathode C) E°_cathode + E°_anode D) E°_anode + E°_cathode

26. For the reaction Mⁿ⁺ + ne⁻ → M, if the concentration of Mⁿ⁺ increases, the electrode potential (E) will:

A) Increase B) Decrease C) Remain unchanged D) Become zero

27. The Nernst equation is derived from which thermodynamic relationship?

A) ΔG = -nFE_cell B) ΔG° = -nFE°_cell C) ΔG = ΔH - TΔS D) PV = nRT

28. In a fuel cell, the electrodes are typically made of:

A) Glass B) Platinum or other catalytic materials C) Wood D) Plastic

29. What is the primary component of the electrolyte in many alkaline hydrogen-oxygen fuel cells?

A) Sulfuric acid B) Potassium hydroxide solution C) Sodium chloride solution D) Distilled water

30. Electrode potential is an intensive property. What does this mean?

A) It depends on the amount of substance. B) It does not depend on the amount of substance. C) It is always zero. D) It is always positive.

31. If E°_cell is positive, the reaction is:

A) Non-spontaneous under standard conditions B) Spontaneous under standard conditions C) At equilibrium under standard conditions D) Impossible under standard conditions

32. What is the equilibrium constant (K) for a redox reaction when E_cell = 0?

A) K < 1 B) K > 1 C) K = 1 D) K is undefined

33. The relationship between E°_cell and K at 298 K is given by:

A) E°_cell = (RT/nF) ln K B) E°_cell = (2.303RT/nF) log K C) E°_cell = (0.0591/n) log K D) E°_cell = -(0.0591/n) log K

34. Which of the following is NOT a factor affecting electrode potential?

A) Concentration of ions B) Temperature C) Pressure of gases D) Color of the solution

35. In an electrolytic cell, the anode is connected to the:

A) Negative terminal of the power supply B) Positive terminal of the power supply C) Battery D) Galvanometer

36. In an electrolytic cell, the cathode is connected to the:

A) Positive terminal of the power supply B) Negative terminal of the power supply C) External circuit D) Electrolyte

37. What happens to the electrode potential of a metal when its cation concentration in solution decreases?

A) It increases B) It decreases C) It remains the same D) It becomes zero

38. The standard reduction potential of Cu²⁺/Cu is +0.34 V and that of Zn²⁺/Zn is -0.76 V. The standard cell potential (E°_cell) for the reaction Zn + Cu²⁺ → Zn²⁺ + Cu is:

A) +0.42 V B) -0.42 V C) +1.10 V D) -1.10 V

39. What is the unit of electrode potential?

A) Ampere B) Volt C) Ohm D) Coulomb

40. Which of the following is a characteristic of a fuel cell that makes it environmentally friendly?

A) It produces greenhouse gases. B) Its primary emission is water. C) It requires large amounts of fossil fuels. D) Its efficiency is very low.

41. The Nernst equation can be used to calculate the cell potential under conditions of:

A) Standard temperature and pressure only B) Non-standard temperature and pressure C) Equilibrium D) Zero Gibbs free energy change

42. What is the role of electrons in the external circuit of an electrochemical cell?

A) They are carried by ions. B) They flow from the cathode to the anode. C) They flow from the anode to the cathode. D) They are consumed in the electrolyte.

43. If Q < 1 in the Nernst equation, the term -(RT/nF) ln Q will be:

A) Negative B) Positive C) Zero D) Indeterminate

44. Which of the following is a disadvantage of hydrogen as a fuel in fuel cells?

A) It is abundant. B) It is non-polluting. C) It is difficult to store and transport. D) It has high energy density.

45. The potential difference that drives the flow of electrons in the external circuit is called:

A) Electrode potential B) Cell potential (EMF) C) Standard potential D) Ionic potential

46. What is the main reason for using catalytic electrodes in fuel cells?

A) To increase resistance B) To decrease the rate of reaction C) To increase the rate of electrochemical reactions D) To act as insulators

47. If the reaction quotient Q is very large, the electrode potential E will be:

A) Close to E° B) Significantly lower than E° C) Significantly higher than E° D) Zero

48. The Nernst equation is essential for understanding:

A) Only standard electrode potentials B) How electrode potentials change with concentration C) The physical properties of metals D) The chemical bonding in molecules

49. A fuel cell that uses molten carbonate as an electrolyte operates at high temperatures. This is typically a:

A) Proton Exchange Membrane (PEM) fuel cell B) Solid Oxide Fuel Cell (SOFC) C) Alkaline Fuel Cell (AFC) D) Phosphoric Acid Fuel Cell (PAFC)

50. Which of the following statements about electrode potentials is correct?

A) Oxidation potential is always equal to reduction potential. B) Oxidation potential is the negative of the reduction potential for the same electrode. C) Oxidation potential is always greater than reduction potential. D) Oxidation potential is always less than reduction potential.

Electrochemical cells electrode potentials Nernst equation and fuel cells - Online Test

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