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 11 of 35
- A. +4
- B. +2
- C. +6
- D. +5
- E. +7
Explanation: Oxide ion has a charge of -2. Three oxide ions will thus have a charge of -6 H has a charge of +1. N is HNO3 will thus be: -6+1+x=0 x=+5.
Correct answer: +5- A. 1
- B. 3
- C. 0
- D. -1
- E. -3
Explanation: All the elements have an oxidation number of 0 in the free state.
Correct answer: 0- A. Oxidation reaction
- B. Reduction reaction
- C. Auto-oxidation and reduction reaction
- D. Substitution reaction
- E. Addition reaction
Explanation: Auto-oxidation and reduction reaction is a reaction in which the same element is oxidized as well as reduced.
Correct answer: Auto-oxidation and reduction reaction- A. bromine is reduced and water Is oxidized
- B. bromine is both reduced and oxidized
- C. bromine is oxidized and carbonate is reduced
- D. bromine is neither reduced or oxidized
Explanation: The oxidation state of bromine in Br2 is 0. It is reduced to bromide ion where its oxidation number is -1 and it is oxidized to BrO3-1…
Correct answer: bromine is both reduced and oxidized205. When electricity is passed through water in the presence of an acid, oxygen and _ are produced.
- A. Carbon
- B. CO
- C. CO2
- D. Hydrogen
Explanation: When electric current is passed through water, water dissociates into hydrogen and oxygen.
Correct answer: Hydrogen- A. Gold, silver, magnesium, aluminum
- B. Mercury, calcium, sodium, magnesium
- C. Sodium, aluminum, lead, copper
- D. Potassium, silver, magnesium, aluminum
Explanation: In order to learn reactivity we have to memorize the electrochemical series.
Correct answer: Sodium, aluminum, lead, copper- A. +4
- B. +6
- C. -2
- D. +2
Explanation: Let the Oxidation number of Sulfur in S2O32- be x. Thus; 2x+(-2 x 3)= -2 2x - 6= -2 2x= -2+6 2x=4 x=4\2 x=2 So, the oxidation state of…
Correct answer: +2- A. -1
- B. +1
- C. -2
- D. 0
Explanation: The most common oxidation state of halogens is -1. Halogens are the most electronegative elements of the periodic table.
Correct answer: -1- A. Decreases
- B. Increases
- C. Remains constant
- D. Both decreases and increases
Explanation: A loss of negatively charged electrons corresponds to an increase in oxidation number, while a gain of electrons corresponds to a decrease…
Correct answer: Increases- A. Oxidation reduction
- B. Addition reaction
- C. Substitution reaction
- D. Autoxidation reaction
- E. Reduction reaction
Explanation: The above reaction is an example of chlorination. Chlorination is the substitution of hydrogen atoms for chlorine atoms.
Correct answer: Substitution reaction- A. Fe is reduced
- B. Fe is oxidized
- C. Cl2 oxidized
- D. None of the above
Explanation: The Oxidation state of iron(Fe) is changed from "0" to "+3". Hence it is oxidised.
Correct answer: Fe is oxidized- A. Electrolyte
- B. Electrolysis
- C. Metallic conductor
- D. None of the above
Explanation: Electrolysis is a process by which an electric current is passed through a substance to effect a chemical change.
Correct answer: Electrolysis- A. Reduction potential will increase
- B. Reduction potential will decrease
- C. Oxidizing ability increase
- D. None of them
Explanation: Moving down the electrochemical series, the reduction potential will increase.
Correct answer: Reduction potential will increase- A. Not feasible
- B. Feasible
- C. Impossible
- D. No indication
Explanation: The more positive the potential, the greater the species' affinity for electrons, or the more the species tends to be reduced.
Correct answer: Feasible- A. Thermolysis
- B. Catalysis
- C. Electrolysis
- D. Photolysis
Explanation: 'Electrolysis' is the breakdown of a substance with the use of electricity.
Correct answer: Electrolysis- A. Na + Fe 3+ -> Na + + Fe
- B. Zn + Ag + -> Zn 2+ + Ag
- C. 3Na + Fe3+ -> 3Na+ + Fe
- D. 2Zn + Ag+ -> 2Zn2+ + Ag
Explanation: To check if the redox reaction equation is balanced, the number of atoms and charges should be balanced on both sides of the equation.
Correct answer: 3Na + Fe3+ -> 3Na+ + Fe- A. +4
- B. -4
- C. +3
- D. +2
Explanation: The oxidation number is the apparent charge on an atom of an element in a molecule or ion. It may be positive, negative, or zero.
Correct answer: +3- A. KOH
- B. NaCl (aq)
- C. NaNO3
- D. Molten NaCl
Explanation: The electrolyte used in a fuel cell can vary depending on the type of fuel cell technology.
Correct answer: KOH- A. Mg
- B. Pt
- C. Zn
- D. Ca
Explanation: The metal that does not liberate hydrogen in reaction with acids is gold (Au).
Correct answer: Pt- A. Ni2+ + Zn -> Zn2+ + Ni
- B. Zn2+ + Ni -> Ni2+ + Zn
- C. Zn2+ + Ni2+ -> Zn + Ni
- D. Zn + Ni -> Zn2+ + Ni2+
Explanation: In the given cell, Zn is oxidized to Zn2+ ions, and Ni2+ ions are reduced to Ni atoms. The anode is Zn, and the cathode is Ni.
Correct answer: Ni2+ + Zn -> Zn2+ + Ni