Free Redox Reactions MCQs with Answers
102 Redox Reactions MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Redox reactions involve oxidation and reduction occurring together, with electrons transferred between species or oxidation numbers changing. The topic covers assigning oxidation states, identifying oxidizing and reducing agents, balancing redox equations by oxidation number or half-reaction methods, and connecting chemical changes with galvanic and electrolytic cells.
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102 questions · page 5 of 6
- A. Ethane
- B. Potassium iodate (V)
- C. Sodium hydroxide
- D. Potassium hydroxide
Explanation: Chlorine reacts with sodium hydroxide to give NaCl and NaClO where oxidation states of Cl are different.
Correct answer: Sodium hydroxide- A. ZnSO4
- B. FeSO4
- C. AgNO3
- D. All of the above
Explanation: For a metal to be displaced in a salt solution, the metal being added must be more reactive than the metal cation in the salt.
Correct answer: AgNO383. Which one of the following chemical reactions is represented by the equation: CI2+kBr ➔ KCl + Br2?
- A. Decomposition
- B. Redox
- C. Hydration
- D. Precipitation
Explanation: In a redox reaction, one substance is oxidized during the reaction (oxidation number increases) and another is reduced (oxidation number…
Correct answer: Redox- A. CrOCl2
- B. COCl2
- C. CrO2Cl2
- D. CrCl6
Explanation: When a mixture of K2CR2O7 and metal chloride is added in warm conc: H2SO4 Chromyl chloride ( CrO2Cl2) which forms a deep reddish brown…
Correct answer: CrO2Cl2- A. 216
- B. 324
- C. 432
- D. 540
Explanation: Explanation for this question will be added soon.
Correct answer: 432- A. Option A
- B. Option B
- C. Option C
- D. None
Explanation: Kolbe's electrolysis method is a general method of preparation of substituted hydrocarbons from the substituted carboxylic acids by the…
Correct answer: Option A87. Primary cells are used in calculators for long-service life the desirable quality of the cell is:
- A. Low energy densities
- B. No self discharge rates
- C. High self-discharge rates
- D. High energy densities
Explanation: A desirable quality of primary cells used in calculators is low or no self-discharge rates, meaning they retain their stored energy for…
Correct answer: No self discharge rates- A. Smelting
- B. Reasing
- C. Reduction
- D. Refining
Explanation: When metals are obtained from sulfide ores, the first step is typically smelting.
Correct answer: Smelting- A. Cathode
- B. Anode
- C. External conductor
- D. Cathode and anode
Explanation: In a Galvanic cell, the redox reaction occurs at two different electrodes, the cathode, and the anode.
Correct answer: Anode- A. that is required for the preparation of bleaching powder
- B. site free when excess of sulphuric acid is added to the bleaching powder
- C. that is required for the generation of hypochlorine
- D. Both B and C
Explanation: The bleaching action of bleaching powder is due to the release of "available chlorine" when it comes into contact with an acidic…
Correct answer: that is required for the generation of hypochlorine- A. Zn + Cu2+ → Zn2+ + Cu
- B. Zn2+ + Cu → Cu2+ + Zn
- C. 2 Fe(OH)3 → 2 Fe + 3/2 O2 + 3 H2O
- D. 2NaCl → 2Na + Cl2
Explanation: A spontaneous chemical reaction is one that occurs without continuous external energy input, often characterized by a negative Gibbs free…
Correct answer: Zn + Cu2+ → Zn2+ + Cu- A. K2Cr2O7 (Potassium dichromate)
- B. Iodine (I2)
- C. KMnO4 (Potassium permanganate)
- D. H2O2 (Hydrogen peroxide)
Explanation: Potassium permanganate (KMnO4) is used as its own indicator because it changes color distinctly at the endpoint of a titration in an…
Correct answer: KMnO4 (Potassium permanganate)- A. Cu only
- B. Zn only
- C. Cu & Ni only
- D. Ni and Zn only
Explanation: The correct answer is Zn only. Zinc has a standard reduction potential of -0.76 V, which is more negative than iron's -0.41 V.
Correct answer: Zn only- A. Pb is converted to PbO2
- B. PbSO4 is converted to Ph
- C. Pb is converted to PbSO4
- D. None of the above
Explanation: Pb oxidized to PBSO4When the battery is discharging, it acts as a galvanic cell and the following chemical reaction occurs:Negative:Pb(s)…
Correct answer: Pb is converted to PbSO4- A. Lead
- B. Lead oxide
- C. Lead hydroxide
- D. None of the above
Explanation: In a lead storage battery, the cathode is made up of lead dioxide, alternatively we can also use lead oxide as it is still an oxide of…
Correct answer: Lead oxide- A. Chloride is oxidized and sodium is reduced
- B. Chlorine acts as an oxidizing agent and sodium as a reducing agent
- C. Chlorine acts as a reducing agent
- D. None of the above
Explanation: In the reaction 2Na(s) + Cl2(g) ⟶ 2NaCl(s), sodium (Na) is oxidized to Na+, losing electrons, and thus acts as the reducing agent.
Correct answer: Chlorine acts as an oxidizing agent and sodium as a reducing agent97. If one Faraday was to be 30,230 coulombs instead of 96,500 coulombs then charge on an electron is:
- A. 1.5 x 10^-19C
- B. 1 x 10^-19C
- C. 0.5 x 10^-19C
- D. 6.02 x 10^-19C
Explanation: The correct answer is 0.5 x 10-19C. A Faraday represents the total charge of one mole of electrons.
Correct answer: 0.5 x 10^-19C- A. Zn + Cu²+ → Zn²+ + Cu
- B. Fe + H2O → Fe2+ + OH-
- C. 2H2 + O2 → 2H2O
- D. Ag+ + Cl- → AgCl
Explanation: The correct answer is the reaction Zn + Cu²+ → Zn²+ + Cu. This reaction is spontaneous because it has a positive standard cell potential…
Correct answer: Zn + Cu²+ → Zn²+ + Cu- A. Corrosion cannot be eliminated completely
- B. Employing modern techniques corrosion can be completely eliminates.
- C. Corrosion process can be slowed down by certain methods.
- D. The presence of acidic oxide in the environment can accelerate the process of corrosion.
Explanation: Option B is correct as corrosion can be eliminated using modern techniques
Correct answer: Employing modern techniques corrosion can be completely eliminates.- A. BO2-
- B. SnO32
- C. S2O34-
- D. MnO42-
Explanation: It is a fact and has to be learntThe correct answer is D) MnO42-.MnO42- is unstable in solution because it can disproportionate to form…
Correct answer: MnO42-