11. The potential of a galvanic cell depends on:
- a) The nature of the electrodes and the concentration of electrolytes
- b) The temperature only
- c) The volume of the electrolyte
- d) The surface area of the salt bridge
Answer: a) The nature of the electrodes and the concentration of electrolytes
Explanation: The cell potential is affected by the type of electrodes used, the concentration of the electrolyte solutions, and temperature, according to the Nernst equation.
12. Which of the following reactions occurs at the cathode in an electrochemical cell?
- a) Reduction
- b) Oxidation
- c) Electrolysis
- d) Ionization
Answer: a) Reduction
Explanation: In both galvanic and electrolytic cells, reduction (gain of electrons) occurs at the cathode.
13. If the standard reduction potential of a half-cell is negative, it means that:
- a) The substance is easily reduced
- b) The substance is easily oxidized
- c) The cell potential is zero
- d) The reaction will never occur
Answer: b) The substance is easily oxidized
Explanation: A negative reduction potential indicates that the substance has a lower tendency to gain electrons and will more readily undergo oxidation.
14. The electrolyte in a dry cell is usually:
- a) Zinc sulfate
- b) Ammonium chloride
- c) Sodium hydroxide
- d) Copper sulfate
Answer: b) Ammonium chloride
Explanation: In a common dry cell (like a zinc-carbon battery), the electrolyte is usually a paste of ammonium chloride.
15. In a lead-acid battery, the anode is made of:
- a) Lead dioxide (PbO₂)
- b) Lead (Pb)
- c) Zinc (Zn)
- d) Nickel (Ni)
Answer: b) Lead (Pb)
Explanation: In a lead-acid battery, the anode is made of lead (Pb), while the cathode is made of lead dioxide (PbO₂).
16. In a Daniell cell, the half-cell reactions involve:
- a) Copper and zinc electrodes
- b) Iron and zinc electrodes
- c) Silver and copper electrodes
- d) Nickel and zinc electrodes
Answer: a) Copper and zinc electrodes
Explanation: The Daniell cell consists of a zinc electrode in a solution of zinc sulfate and a copper electrode in a solution of copper sulfate.
17. Which of the following statements is true for a galvanic cell?
- a) The anode is positive
- b) The cathode is negative
- c) The anode is negative
- d) Both electrodes are neutral
Answer: c) The anode is negative
Explanation: In a galvanic cell, the anode is negative because oxidation occurs there, releasing electrons into the external circuit.
18. The purpose of the external circuit in an electrochemical cell is to:
- a) Allow ions to flow between the electrodes
- b) Transfer electrons from the anode to the cathode
- c) Maintain pH balance
- d) Dissipate heat generated by the reaction
Answer: b) Transfer electrons from the anode to the cathode
Explanation: The external circuit allows the flow of electrons from the anode to the cathode, completing the electrical circuit.
19. The electrode potential of a half-cell depends on:
- a) The nature of the electrode material only
- b) The concentration of the electrolyte only
- c) Both the nature of the electrode and the concentration of the electrolyte
- d) The distance between the electrodes
Answer: c) Both the nature of the electrode and the concentration of the electrolyte
Explanation: The electrode potential is influenced by the type of electrode material and the concentration of the ions in the electrolyte, as per the Nernst equation.
20. In a standard electrochemical cell, the standard conditions are:
- a) 1 M concentration, 25°C, 1 atm pressure
- b) 0.1 M concentration, 25°C, 1 atm pressure
- c) 1 M concentration, 100°C, 1 atm pressure
- d) 0.5 M concentration, 0°C, 1 atm pressure
Answer: a) 1 M concentration, 25°C, 1 atm pressure
Explanation: Standard electrode potentials are measured under standard conditions, which are 1 M concentration of ions, 25°C (298 K) temperature, and 1 atm pressure.
Leave a comment