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.
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Read the Electrochemistry notesFree MDCAT chapter notes with key terms696 questions · page 23 of 35
- A. MnO2-4→ MnO2
- B. MnO-4→ Mn+2
- C. CrO2-4→ Cr+3
- D. Cr2O2-7 → 2Cr+3
Explanation: A. MnO2-4→ MnO2 oxidation number of Mn in MnO4-2 is +6 and in MnO2 is +4. Hence there is transfer of two electrons.B.
Correct answer: MnO2-4→ MnO2- A. Oxidation and reduction
- B. Reduction and hydrolysis
- C. Reduction and oxidation
- D. Oxidation and hydrolysis
Explanation: Oxidation takes place at anode and reduction takes place at cathode.
Correct answer: Oxidation and reduction- A. Na and Cl2
- B. H2 and Cl2
- C. Na and NaOH
- D. H2, Cl2 and NaOH
Explanation: In the electrolysis of molten NaCl, sodium ions (Na+) move to the cathode where they gain electrons to form sodium metal (Na).
Correct answer: Na and Cl2444. During the electrolysis of aqueous KNO3, H2 is produced at cathode instead of potassium due to:
- A. Reduction potential of "K" is greater than hydrogen
- B. Hydrogen is more reactive than potassium
- C. Reduction potential of potassium is less than hydrogen
- D. All of the above are possible reassons
Explanation: Reduction potential of potassium is less than hydrogen. H+ will be reduced instead of K+ at cathode and hydrogen gas is produced.K+ +…
Correct answer: Reduction potential of potassium is less than hydrogen- A. Reduction
- B. Both oxidation and reduction
- C. Oxidation
- D. Neither oxidation nor reduction
Explanation: Electrolysis of dilute H2SO4:At anode: O2 is produced (Oxidation)At cathode: H2 is produced (Reduction)
Correct answer: Reduction- A. H2
- B. Cl2
- C. O2
- D. Na
Explanation: In the electrolysis of aqueous sodium chloride (NaCl), water molecules are reduced at the cathode rather than sodium ions because water…
Correct answer: H2- A. Cathode
- B. Solution
- C. Anode
- D. Both A & B
Explanation: Electrolytic cell is used for the purification of copper. Impure copper is made the anode and thin sheet of pure copper is made the…
Correct answer: Anode- A. Temperature
- B. Concentration of ions
- C. Nature of electrolyte
- D. All of these
Explanation: As reduction potential of electrodes changes due to change in: i) Temperatureii) Concentration of ions iii) Nature of electrolyteHence…
Correct answer: All of these- A. Standard reduction potential
- B. Standard electrode potential
- C. Reduction potential
- D. Both "A" and "C"
Explanation: Standard electrode potential is measured at 298 K for electrode in 1M aqueous solution of its ions.
Correct answer: Standard electrode potential- A. Electromotive force (Emf)
- B. Electrode potential
- C. Cell potential
- D. Both A and C
Explanation: The correct answer is 'Both A and C' because 'Electromotive force' (Emf) and 'Cell potential' are related concepts.
Correct answer: Both A and C- A. It is the difference of potential of a cell, consisting of particular electrode and the SHE
- B. The potential set up, when an electrode is in contact with one molar solution of its ions at standard conditions
- C. The electrode potential of a single electrode can be measured directly
- D. Both A and B
Explanation: Electrode potential is measured by comparing it with SHE.
Correct answer: The electrode potential of a single electrode can be measured directly- A. Finely divided platinum black is used as electrode
- B. Temperature is kept 25°C
- C. One molar solution of H2SO4 is used as electrolyte
- D. Electrode potential of any element can be calculated by comparison method
Explanation: The Standard Hydrogen Electrode (SHE) is used as a reference electrode in electrochemistry.
Correct answer: One molar solution of H2SO4 is used as electrolyte- A. H2(gas) ⟶ 2H+(aq) + 2e-
- B. 2H2O(I) → 2H2(g) + O2(g)
- C. 2H+(aq) + 2e- → H2(gas)
- D. 2H2O(I) + 2e- → OH-(aq) + H2(g)
Explanation: The Standard Hydrogen Electrode (SHE) serves as a reference for measuring electrode potentials.
Correct answer: H2(gas) ⟶ 2H+(aq) + 2e-- A. Reference
- B. Arbitrary
- C. Exact
- D. Experimental
Explanation: SHE itself is a reference electrode. Hence, its E*red is taken as zero which is an arbitrary value i.e. without any other reference.
Correct answer: Arbitrary- A. pH scale
- B. Redox scale
- C. Arrhenius scale
- D. Hydrogen scale
Explanation: The correct answer is the 'Redox scale.' The Electrochemical Series is a list of elements and ions sorted by their standard electrode…
Correct answer: Redox scale- A. Zn has less reduction potential than hydrogen and Cu more
- B. Zn has high oxidizing potential than hydrogen and Cu more
- C. Zn is above in electrochemical series than hydrogen and Cu below
- D. All the above are correct
Explanation: In ECS , Cu has less reduction potential than hydrogen and Zinc. Zn is above in ECS and Cu is below.
Correct answer: All the above are correct- A. Increased
- B. Decreased
- C. Dropped to zero
- D. Electrodes will be reversed
Explanation: Salt bridge maintain the electrical neutrality between two half cells preventing net charge accumulation which will occur.
Correct answer: Dropped to zero- A. A1
- B. Zn
- C. H2
- D. KCI
Explanation: A1 -oxidation- Al+3+3e-, as A1 is oxidized hence it acts as anode while zinc will act as cathode and is reduced.
Correct answer: A1- A. N
- B. F
- C. O
- D. Cl
Explanation: Fluorine has the highest reduction potential in the electrochemical series, indicated by its standard reduction potential of Eered =…
Correct answer: F- A. Below SHE
- B. Above SHE
- C. Equal to SHE
- D. Both A and B
Explanation: In ECS clements above SHE have negative E∘red ,E∘oxi = - E∘red. Hence elements with negative E∘red have positive E∘oxi.
Correct answer: Above SHE