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 18 of 35
- A. 0
- B. Positive
- C. Negative
- D. Fractional
Explanation: The oxidation number for an element in its elemental form is 0 (holds true for isolated atoms and elemental substances which bond…
Correct answer: 0- A. O2, H2
- B. O2, Na
- C. O2, SO
- D. O2, S2O4-2
Explanation: Explanation: This question can be solved by recalling the order of the electrochemical series: From this, it can be seen that H+ will be…
Correct answer: O2, H2- A. NaF
- B. NaCl
- C. Na₂O
- D. MgO
Explanation: The oxidation states of all the atoms in the given options are as follows: Na1+Cl1- Na1+F1- Na(1+)2O2- Mg2+O2-
Correct answer: MgO- A. High
- B. None of these
- C. Same
- D. Low
Explanation: Since weak electrolytes do not completely dissociate in aqueous solutions, they are less soluble in water.
Correct answer: Low- A. Changing positions of electrodes
- B. Replacing salt bridge with a wire
- C. Providing an external source of electricity
- D. All of these
Explanation: To convert a voltaic cell into an electrolytic cell, an external source of electricity is required.
Correct answer: Providing an external source of electricity- A. 0
- B. +1
- C. 2
- D. -1
Explanation: .Metal hydrides are defined as compounds that are formed when a metal element is bonded to hydrogen.
Correct answer: -1- A. +2
- B. +4
- C. +6
- D. +7
Explanation: The oxidation number of Mn in K2MnO4 can be calculated as follows; 2(K) + Mn + 4(O) = 0 As we know that oxidation nimber of K is +1 and…
Correct answer: +6- A. zero
- B. Negative
- C. Positive
- D. Greater than zero
Explanation: In electrochemical series, the elements present above hydrogen have negative reduction potential while those below hydrogen have positive…
Correct answer: Negative- A. -1
- B. 2
- C. -2
- D. 1
Explanation: In peroxides, the oxidation number of oxygen is -1. This is due to the peroxide ion (O2²⁻), where two oxygen atoms are bonded together…
Correct answer: -1350. In the reaction,Cr2O72- + 14 H+-> 2 Cr3++7H2OHow many electrons are gained or lost by chromium atom?
- A. +12 e
- B. +3 e-
- C. +6 e
- D. -6 e-
Explanation: In this reaction, each Cr atom goes from a +6 oxidation state (in Cr2O72-) to a +3 oxidation state (in Cr3+). So, each atom get 3 electrons.
Correct answer: +3 e-- A. 0
- B. +1
- C. +2
- D. +3
Explanation: The correct oxidation number for free magnesium (in its elemental form) is not 0.
Correct answer: 0- A. Atomic number of zinc is higher than that of copper
- B. Zinc has higher reduction potential than copper
- C. Zinc is more soluble
- D. Zinc has smaller reduction potential than copper
Explanation: Option D is correct because zinc's smaller reduction potential (-0.76V) compared to copper's (+0.34V) signifies that zinc is more…
Correct answer: Zinc has smaller reduction potential than copper- A. III
- B. II
- C. IV
- D. VI
Explanation: In the given complex, [Co(H2NCH2CH2NH2)3]2(SO4)3 Cobalt is bonded with three molecules of ethylenediamine which is a bidendate ligand…
Correct answer: III- A. Hydrogen
- B. Oxygen
- C. Both hydrogen and oxygen
- D. Neither hydrogen nor oxygen
Explanation: hydrogen gas (H₂) is produced at the cathode.Oxygen gas (O₂) is produced at the anode.
Correct answer: Both hydrogen and oxygen- A. 2H+ + 2e -->H2(g)
- B. 2H2O +2e -> H2(g)+2(OH-)
- C. 2(OH-) -> 2H2O + O2(g) +4e
- D. 2H2O -> O2(g) +4H+ + 4e
Explanation: Here's a breakdown of the electrolysis of water:Cathode: Water is reduced to hydrogen gas.
Correct answer: 2H2O -> O2(g) +4H+ + 4e- A. Primary batteries
- B. Secondary batteries
- C. Solar batteries
- D. Fuel batteries
Explanation: Secondary batteries, also known as rechargeable batteries, have high charge density and are designed to be reused multiple times.
Correct answer: Secondary batteries- A. Cl₂ is evolved at the cathode
- B. H₂ is evolved at the cathode
- C. Na is deposited at the cathode
- D. Na appears at the anode
Explanation: H₂ is produced at the cathode due to the reduction of H₂O instead of Na⁺.
Correct answer: H₂ is evolved at the cathode- A. Cl2 at cathode & H2 at anode
- B. H2 at cathode & O2 at anode
- C. None of these
- D. H2 at anode & Na at cathode
- E. H2 at anode & O2 cathode
Explanation: During the electrolysis of dilute hydrochloric acid, the process involves the splitting of water molecules and ions in the solution.
Correct answer: H2 at cathode & O2 at anode- A. H2S
- B. NH3
- C. H2SO4
- D. HNO3
- E. Cl2
Explanation: The oxidation of ammonia takes place, and it is converted into nitric oxide (NO). The process is reversible and exothermic.
Correct answer: NH3- A. NaOH+ H2 are produced at cathode
- B. Cl2 is produced at anode
- C. NaOH+H2 are produced at anode
- D. NaOH+H2 are produced at cathod and Cl2 is produced at anode
- E. Cl2 is produced at cathode
Explanation: In the Castner-Kellner cell, option (d) is correct: NaOH + H2 is produced at the cathode, and Cl2 is produced at the anode.
Correct answer: NaOH+H2 are produced at cathod and Cl2 is produced at anode