Free Electrochemistry MCQs with Answers
696 Electrochemistry MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Electrochemistry describes electron transfer through oxidation and reduction, identifies oxidizing and reducing agents, and applies oxidation numbers to balance redox equations. It also covers electrode potential and the standard hydrogen electrode, which provides the reference for comparing the reduction tendencies of other electrodes.
Last updated
Read the Electrochemistry notesFree MDCAT chapter notes with key terms696 questions · page 6 of 35
- A. Lead storage battery
- B. Silver oxide cell
- C. Fuel cell
- D. Ni-Cd cell
Explanation: Lead-acid batteries, often used in cars, are not easily rechargeable. During discharge, they undergo chemical reactions that are not…
Correct answer: Lead storage battery- A. Pressure increases
- B. Dilution decreases
- C. Dilution increases
- D. None
Explanation: As a weak electrolyte gets more diluted (i.e., when more solvent is added to the solution), the concentration of ions produced by its…
Correct answer: Dilution increases- A. Free electrons
- B. Free molecule
- C. Free ions
- D. Atoms of Na and Cl
Explanation: When NaCl is melted (in its molten state), the crystal lattice breaks down, separating the sodium (Na+) and chloride (Cl-) ions.These…
Correct answer: Free ions- A. Cu^2+ + 2e^- → Cu
- B. Cu+2e^- → Cu^2+
- C. Hg+O2 → HgO
- D. Mg+O2 → MgO
Explanation: This equation represents a reduction reaction where copper ions (Cu^2+) gain electrons (2e^-) to form solid copper (Cu).
Correct answer: Cu^2+ + 2e^- → Cu- A. Spontaneous
- B. non-spontaneous reaction
- C. Neutralization
- D. All of these
Explanation: Electrolytic cells use electrical energy to drive non-spontaneous reactions that wouldn't occur on their own.
Correct answer: non-spontaneous reaction- A. oxidation
- B. Reduction
- C. Redox
- D. Decomposition
Explanation: Anodes involve oxidation, where a species loses electrons and increases its oxidation number.
Correct answer: oxidation- A. +ve ion
- B. -ve ion
- C. Neutral atoms
- D. does not provide any electron
Explanation: Cathodes involve reduction, where electrons are accepted by positively charged cations, reducing their oxidation number.
Correct answer: -ve ion- A. external electric circuit
- B. salt bridge
- C. movement of ions
- D. all of the above
Explanation: The flow of electrons occurs through a complete circuit:(a) Electrons move through the external wire connecting anode and cathode.(b) Ions…
Correct answer: all of the above- A. Al
- B. Zn
- C. Cu electrode
- D. Fe
Explanation: Typically, the right half-cell in a standard oxidation-reduction potential setup uses the Cu/CuSO4 system.
Correct answer: Cu electrode- A. Daniel cell
- B. Down's cell
- C. Voltaic cell
- D. Nelson's cell
Explanation: The correct option for the reaction represented by Zn(s)/Zn²⁺(aq) 1M || Cu²⁺(aq) 1M/Cu is:Voltaic cell.
Correct answer: Voltaic cell- A. New electrode of same element
- B. SHE
- C. 1M solution of ions of respective element
- D. 2M solution of HCl
Explanation: The standard hydrogen electrode (SHE) is the reference electrode assigned a potential of zero volts.
Correct answer: SHE- A. 298K
- B. 300K
- C. 30°C
- D. 310K
Explanation: Standard electrode potentials are measured under standard conditions, which include a temperature of 298K (25°C).
Correct answer: 298K- A. 760mm of Hg
- B. 750mm
- C. 780mm
- D. 800mm
Explanation: The standard hydrogen electrode uses hydrogen gas at a pressure of 1 atm, which corresponds to approximately 760mm of Hg.
Correct answer: 760mm of Hg- A. Oxidation
- B. Reduction
- C. Oxidation-reduction
- D. depends on the nature of the coupled electrode
Explanation: The electrode potential of Zn itself doesn't have a fixed value like "oxidation" or "reduction." It depends on the specific half-cell…
Correct answer: depends on the nature of the coupled electrode- A. higher
- B. lower
- C. in middle
- D. no effect of position
Explanation: In an electrochemical cell, the anode is where oxidation occurs, losing electrons and increasing its oxidation number.
Correct answer: lower- A. Valency
- B. Coordination number
- C. oxidation number
- D. Charge number
Explanation: The oxidation number, also known as formal charge, reflects the apparent charge an atom in a molecule would have if all bonds were purely…
Correct answer: oxidation number117. Voltaic cell is a
- A. Valency
- B. reversible cell
- C. Alkaline cells
- D. all of the above
Explanation: Voltaic cells, also known as galvanic cells, convert chemical energy into electrical energy through spontaneous redox reactions.
Correct answer: reversible cell- A. 40%
- B. 25%
- C. 30%
- D. 50%
Explanation: Lead accumulators typically contain around 30% sulphuric acid (H2SO4) by weight.
Correct answer: 30%- A. 0.76
- B. -0.76 v
- C. -0.55
- D. 0.55 V
Explanation: The standard reduction potential of Zn is approximately -0.76 V, signifying its tendency to undergo oxidation and donate electrons in a…
Correct answer: -0.76 v- A. wire
- B. salt bridge
- C. electric circuit
- D. no connection exists
Explanation: In an electrochemical cell, half cells are separated but need to be connected for the flow of electrons and ions.A wire directly…
Correct answer: salt bridge