Electrochemistry MCQs 2026

Oxidation is defined as the process involving

1. AGain of electrons✓
2. BLoss of electrons✓
3. CGain of protons✓
4. DLoss of protons✓

Reduction is defined as the process involving

1. ALoss of electrons✓
2. BGain of electrons✓
3. CLoss of protons✓
4. DGain of neutrons✓

A redox reaction always involves

1. AOnly oxidation✓
2. BBoth oxidation and reduction occurring simultaneously✓
3. COnly reduction✓
4. DNeither oxidation nor reduction✓

The substance that gets oxidized in a redox reaction and causes reduction of another substance is called the

1. AOxidizing agent✓
2. BCatalyst✓
3. CReducing agent✓
4. DElectrolyte✓

The substance that gets reduced and causes oxidation of another substance is called the

1. AReducing agent✓
2. BCatalyst✓
3. COxidizing agent✓
4. DElectrode✓

In an electrochemical (galvanic/voltaic) cell, oxidation occurs at the

1. AAnode✓
2. BCathode✓
3. CSalt bridge✓
4. DExternal wire only✓

In an electrochemical (galvanic/voltaic) cell, reduction occurs at the

1. ACathode✓
2. BAnode✓
3. CSalt bridge✓
4. DElectrolyte only✓

In a galvanic cell, electrons flow through the external circuit from the

1. ACathode to the anode✓
2. BAnode to the cathode✓
3. CSalt bridge to the anode✓
4. DCathode to the salt bridge✓

The function of a salt bridge in a galvanic cell is to

1. AGenerate current✓
2. BIncrease voltage✓
3. CMaintain electrical neutrality by allowing ion flow between half-cells✓
4. DAct as the cathode✓

In an electrolytic cell, electrical energy is used to

1. AGenerate spontaneous chemical reactions✓
2. BMeasure pH✓
3. CStore heat✓
4. DDrive a non-spontaneous chemical reaction✓

In an electrolytic cell, the anode is connected to the ___ terminal of the external battery

1. ANegative✓
2. BNeutral✓
3. CPositive✓
4. DGround✓

The oxidation number of oxygen in most compounds is

1. A+2✓
2. B+1✓
3. C-2✓
4. D-1✓

The oxidation number of hydrogen in most compounds is

1. A-1✓
2. B0✓
3. C+1✓
4. D+2✓

The oxidation number of a free element (uncombined) is always

1. AZero✓
2. B+1✓
3. C-1✓
4. DEqual to its group number✓

Electrolysis of molten sodium chloride produces

1. AHydrogen and oxygen✓
2. BSodium metal and chlorine gas✓
3. CSodium hydroxide only✓
4. DSodium and oxygen✓

Electroplating uses the principle of

1. ACombustion✓
2. BNeutralization✓
3. CDistillation✓
4. DElectrolysis to deposit a metal coating on an object✓

The standard hydrogen electrode (SHE) is assigned a standard reduction potential of

1. A0.00 V✓
2. B1.00 V✓
3. C-1.00 V✓
4. D2.00 V✓

A metal with a more positive standard reduction potential than hydrogen will

1. ADisplace hydrogen from acids✓
2. BNot readily displace hydrogen from dilute acids✓
3. CAlways corrode faster✓
4. DAlways be a stronger reducing agent than hydrogen✓

According to the electrochemical (activity) series, the most reactive metal listed is generally

1. AGold✓
2. BCopper✓
3. CSilver✓
4. DPotassium✓

According to the electrochemical series, the least reactive metal (most easily reduced) is generally

1. AGold✓
2. BSodium✓
3. CPotassium✓
4. DZinc✓

A spontaneous redox reaction has a standard cell potential (E°cell) that is

1. AZero✓
2. BNegative✓
3. CUndefined✓
4. DPositive✓

The relationship between Gibbs free energy and cell potential is given by

1. AΔG° = nFE°✓
2. BΔG° = −nFE°✓
3. CΔG° = nF/E°✓
4. DΔG° = E°/nF✓

In a Daniell cell, the two electrodes used are

1. ACopper and silver✓
2. BZinc and silver✓
3. CCopper and gold✓
4. DZinc and copper✓

In a lead-acid battery (car battery), the electrolyte used is

1. ASodium chloride solution✓
2. BPotassium hydroxide✓
3. CAmmonium chloride paste✓
4. DDilute sulfuric acid✓

A dry cell (common battery) uses ___ as its electrolyte

1. AAmmonium chloride paste (or zinc chloride paste)✓
2. BDilute sulfuric acid✓
3. CMolten sodium chloride✓
4. DPure water✓

Corrosion of iron (rusting) is fundamentally an example of

1. AReduction only✓
2. BAn electrochemical (redox) process✓
3. CA physical change only✓
4. DNeutralization✓

Galvanization protects iron from rusting by coating it with a layer of

1. ACopper✓
2. BZinc✓
3. CSilver✓
4. DGold✓

Faraday's first law of electrolysis states that the mass of a substance deposited at an electrode is directly proportional to the

1. AVoltage applied✓
2. BResistance of the circuit✓
3. CVolume of electrolyte✓
4. DQuantity of electric charge passed through the electrolyte✓

Faraday's second law of electrolysis relates the mass of substances deposited by the same quantity of charge to their

1. AEquivalent masses✓
2. BBoiling points✓
3. CDensities✓
4. DColors✓

The unit of electric charge used in Faraday's laws, one Faraday, is approximately equal to the charge on

1. AOne mole of electrons (96,500 C)✓
2. BOne electron only✓
3. COne mole of protons only✓
4. DOne coulomb✓

A fuel cell generates electricity through the electrochemical reaction of

1. ACoal and oxygen✓
2. BSodium and chlorine✓
3. CHydrogen and oxygen✓
4. DZinc and copper✓

Which of the following is a secondary (rechargeable) cell

1. ADry cell✓
2. BSimple voltaic cell✓
3. CDaniell cell✓
4. DLead-acid battery✓

A primary cell is one that

1. ACan be recharged indefinitely✓
2. BUses only solid electrolytes✓
3. CCannot be recharged once its reactants are consumed✓
4. DGenerates no electric current✓

In an electrolytic cell used for electrorefining of copper, the impure copper is used as the

1. ACathode✓
2. BSalt bridge✓
3. CElectrolyte✓
4. DAnode✓

During electrorefining of copper, pure copper is deposited at the

1. ACathode✓
2. BAnode✓
3. CSalt bridge✓
4. DElectrolyte solution only✓

The SI unit of electrode potential is the

1. AAmpere✓
2. BCoulomb✓
3. CVolt✓
4. DOhm✓

Which of the following metals would displace copper from copper sulfate solution

1. ASilver✓
2. BGold✓
3. CMercury✓
4. DZinc✓

The oxidation state of chlorine in NaCl is

1. A-1✓
2. B+1✓
3. C0✓
4. D-2✓

The oxidation state of manganese in KMnO4 is

1. A+6✓
2. B+7✓
3. C+5✓
4. D+4✓

The process of purifying an impure metal using electrolysis is called

1. AGalvanization✓
2. BAnodizing✓
3. CElectrorefining✓
4. DElectroplating✓

Anodizing is an electrolytic process most commonly used to increase the thickness of the natural oxide layer on

1. AAluminum✓
2. BIron✓
3. CCopper✓
4. DZinc✓

A concentration cell generates electric current due to a difference in the

1. AElectrode material only✓
2. BConcentration of the electrolyte solutions in the two half-cells✓
3. CTemperature of the electrodes✓
4. DColor of the solutions✓

In the electrolysis of aqueous sodium chloride (brine), the gas produced at the cathode is

1. AChlorine✓
2. BOxygen✓
3. CHydrogen✓
4. DNitrogen✓

In the electrolysis of aqueous sodium chloride (brine), the gas produced at the anode is

1. AChlorine✓
2. BHydrogen✓
3. COxygen✓
4. DNitrogen✓

A cell in which the overall reaction produces electrical energy from a spontaneous chemical reaction is called a

1. AGalvanic (voltaic) cell✓
2. BElectrolytic cell✓
3. CConcentration gradient only✓
4. DFuel-only cell✓

The standard electrode potential of a half-cell is measured relative to the

1. AZinc electrode✓
2. BCopper electrode✓
3. CCalomel electrode only✓
4. DStandard hydrogen electrode✓

Which of the following processes occurs at the cathode in any electrochemical cell (galvanic or electrolytic)

1. AOxidation always✓
2. BLoss of electrons✓
3. CFormation of anions only✓
4. DReduction (gain of electrons)✓

Which of the following best defines an electrolyte

1. AA substance that never conducts electricity✓
2. BA metal that conducts electricity in solid form✓
3. CA substance that conducts electricity in molten or dissolved (aqueous) form due to ion movement✓
4. DA gas that conducts electricity when heated✓

In the reactivity series, metals above hydrogen can generally

1. ANot react with dilute acids✓
2. BDisplace hydrogen from dilute acids✓
3. COnly react with bases✓
4. DReact only with water, never acids✓

The number of electrons transferred when Fe2+ is oxidized to Fe3+ is

1. A2✓
2. B3✓
3. C1✓
4. D0✓