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 3 of 35
- A. CuSO4
- B. AgNO3
- C. K2MnO4
- D. CH3COOH
Explanation: AgNO3 produces black spots on skin and cellulose because light or organic matter reduces Ag+ to finely divided metallic silver, which…
Correct answer: AgNO3- A. NaHSO3
- B. Na2S2O3
- C. Na2S
- D. Na2SO3
Explanation: Sodium thiosulfate, Na2S2O3, is used as photographic fixer because it dissolves unexposed silver halide by forming a soluble…
Correct answer: Na2S2O3- A. Free radicals
- B. Cosmic rays
- C. Nitrogen oxides
- D. UV -rays
Explanation: Ultraviolet rays split O2 molecules into oxygen atoms, and these atoms then combine with O2 to form O3 in the upper atmosphere.
Correct answer: UV -rays- A. +ve
- B. -ve
- C. Neutral
- D. None
Explanation: A cation forms when an atom or group loses one or more electrons, leaving more protons than electrons and giving a positive charge.
Correct answer: +ve- A. Zinc
- B. Carbon (Graphite)
- C. ZnCl²
- D. MnO²(Pyrolusite)
Explanation: In a zinc-carbon dry cell, the graphite rod serves as the cathode and conducts electrons from the manganese dioxide cathodic mixture.
Correct answer: Carbon (Graphite)- A. Electrolytic cell
- B. Galvanic cell
- C. Daniel cell
- D. Not
Explanation: An electrolytic cell requires an external electrical source to drive a non-spontaneous redox reaction, so its cell reaction does not…
Correct answer: Electrolytic cell- A. Nitrification
- B. Fermentation
- C. Denitrification
- D. None of these
Explanation: Nitrification is the bacterial oxidation of ammonia or ammonium compounds first to nitrite and then to nitrate, NO3−.
Correct answer: Nitrification- A. K2Cr2O7
- B. H2SO4
- C. SO3
- D. P2O5
Explanation: SO2 is a reducing agent and reduces orange dichromate ions, Cr2O7^2-, to green Cr3+ ions in acidic solution.
Correct answer: K2Cr2O7- A. 4.8
- B. 5.2
- C. 8.8
- D. 8.4
Explanation: For hydrogen peroxide decomposition, 1 equivalent of H2O2 produces 5.6 L of O2 at STP per litre of a 1 N solution.
Correct answer: 8.4- A. 10 grams of H2O2 solution liberate 10 mL of O2 at STO
- B. 10 gram equivalents of H2O2 liberates 10 mL of O2 at STP
- C. 10 litres of H2O2 liberates 19 mL of O2 at STP
- D. 1mL of solution of H2O2 liberates 10 mL of O2 at STP
Explanation: A 10-volume H2O2 solution liberates 10 mL of oxygen gas at STP from every 1 mL of the solution.
Correct answer: 1mL of solution of H2O2 liberates 10 mL of O2 at STP- A. C
- B. Zn
- C. Al
- D. Cu
Explanation: Carbon acts as a reducing agent during smelting because it removes oxygen from metal oxides, producing the metal and carbon monoxide or…
Correct answer: C- A. Reduce it
- B. Oxidize it
- C. Obtain an alloy
- D. Separate volatile impurities
Explanation: Smelting uses heat and a reducing agent to convert a concentrated metal oxide into the free metal, so its main purpose is reduction.
Correct answer: Reduce it- A. 2
- B. 3
- C. 4
- D. 5
Explanation: Nitric acid is a strong acid, so a 0.001 mol L^-1 HNO3 solution dissociates almost completely and gives [H+] = 0.001 mol L^-1 = 10^-3 mol…
Correct answer: 3- A. It is a sterilising agent.
- B. It dissolves the impurities of water.
- C. It is a reducing agent.
- D. It is an oxidising agent.
Explanation: Potassium permanganate, KMnO4, oxidises many dissolved organic and microbial impurities, so it helps purify water by acting as an…
Correct answer: It is an oxidising agent.- A. Sulphur dioxide
- B. Sulphuryl chloride
- C. Suphanyl chloride
- D. All of the above
Explanation: The intended reactant is chlorine, Cl2, and SO2 reacts with it in sunlight to form sulfuryl chloride, SO2Cl2.
Correct answer: Sulphuryl chloride- A. H2S2O3
- B. H2SO8
- C. H2S4O6
- D. H2 S2 O6
Explanation: H2SO8 contains a peroxide O-O linkage, represented in its structure as a peroxodisulfuric acid unit.
Correct answer: H2SO8- A. N2O3
- B. NO2
- C. NO
- D. N2O
Explanation: The nitrate ion is reduced to NO, which combines with Fe2+ in acidic solution to form the brown nitrosyl complex, commonly represented as…
Correct answer: NO- A. FeSO4.No
- B. FeSO4.No2
- C. FeSO4.No3
- D. FeSO4.N2o
Explanation: In the brown-ring test, NO formed from nitrate coordinates with Fe2+ to produce a nitrosyl complex, conventionally written in simplified…
Correct answer: FeSO4.No- A. Oxidation
- B. Reduction
- C. Decomposition
- D. Both b & c
Explanation: H3PO3 undergoes disproportionation on heating: some phosphorus(III) is oxidised to phosphorus(V) in H3PO4, while some is reduced to…
Correct answer: Both b & c- A. activation
- B. enameling
- C. corrosion
- D. coating
Explanation: Corrosion is the gradual chemical or electrochemical deterioration of a metal through reaction with oxygen, moisture, acids or other…
Correct answer: corrosion