MCQs — Electrochemistry

Practice questions for Chemistry.

← Back to Electrochemistry

Question 121

Corrosion is best defined as:

A. A physical process with no chemical change involved

B. A natural electrochemical process that occurs when a metal reacts with its environment

C. A process that only occurs in laboratory settings

D. The process of purifying a metal from its ore

Question 122

During corrosion, a metal typically reacts with which two substances present in the atmosphere?

A. Nitrogen and carbon dioxide

B. Oxygen and moisture (water)

C. Hydrogen and helium

D. Only inert gases

Question 123

Corrosion converts refined metals into more chemically stable:

A. Pure metals

B. Metal oxides

C. Noble gases

D. Alloative crystals with no chemical formula

Question 124

The most familiar, everyday example of corrosion is:

A. The tarnishing of gold jewellery

B. The formation of rust on iron

C. The melting of ice

D. The evaporation of water

Question 125

Which two substances are both necessary for iron to rust?

A. Nitrogen and carbon dioxide

B. Oxygen and water

C. Hydrogen and chlorine

D. Only heat, with no chemical substances required

Question 126

Corrosion is fundamentally classified as what type of chemical reaction?

A. An acid-base neutralization reaction

B. An oxidation-reduction (redox) reaction

C. A purely physical change

D. A nuclear reaction

Question 127

A region of a metal surface with relatively LESS moisture tends to act as the:

A. Cathode, where oxygen is reduced

B. Anode, where the metal itself is oxidized

C. Neither anode nor cathode

D. A completely inert region

Question 128

A region of a metal surface with relatively MORE moisture tends to act as the:

A. Anode, where the metal is oxidized

B. Cathode, where atmospheric oxygen is reduced

C. Neither anode nor cathode

D. A completely inert region

Question 129

At the anodic region of a corroding iron surface, the half-reaction that occurs is best represented as:

A. Fe(s) -> Fe2+(aq) + 2e-

B. Fe2+(aq) + 2e- -> Fe(s)

C. O2 + 2H2O + 4e- -> 4OH-

D. Fe(s) + O2 -> FeO2

Question 130

At the cathodic region of a corroding iron surface, atmospheric oxygen is reduced according to the half-reaction:

A. O2 + 2H2O + 4e- -> 4OH-

B. Fe(s) -> Fe2+(aq) + 2e-

C. 4OH- -> O2 + 2H2O + 4e-

D. Fe2+(aq) -> Fe(s) + 2e-

Question 131

Explain how the Fe2+ ions formed at the anodic region eventually contribute to the formation of rust.

A. The Fe2+ ions remain fixed at the anode and never move or react further

B. The Fe2+ ions flow through the moisture on the metal's surface toward the cathodic region, where they further react with oxygen to form rust

C. The Fe2+ ions instantly evaporate into the atmosphere

D. The Fe2+ ions are converted directly back into iron metal, preventing rust

Question 132

Rust is chemically represented by the formula:

A. FeO

B. Fe2O3

C. Fe2O3.xH2O

D. FeCl3

Question 133

Coating a metal surface with paint helps prevent corrosion mainly by:

A. Chemically neutralizing the metal's reactivity

B. Forming a protective barrier between the metal surface and its environment

C. Increasing the metal's natural oxidation rate

D. Converting the metal into an alloy

Question 134

Paint is a popular corrosion-prevention method for everyday steel objects (cars, bridges, bikes) mainly because it is:

A. Extremely expensive but highly durable

B. Cheap and can be applied easily

C. Only usable on non-metal surfaces

D. Effective only at very high temperatures

Question 135

Besides preventing corrosion, what additional practical benefit does painting a steel object provide?

A. It permanently increases the object's mass

B. It also provides visual appeal, improving the object's appearance

C. It eliminates the need for the object's structural design

D. It converts the steel into a different metal

Question 136

Alloying reduces the tendency of iron to oxidize mainly by:

A. Removing all of the iron's electrons

B. Combining iron with other metals to form a new material with different, more corrosion-resistant properties

C. Melting the iron completely without adding anything else

D. Simply painting over the iron's surface

Question 137

Adding chromium to iron produces which highly corrosion-resistant alloy?

A. Bronze

B. Brass

C. Stainless steel

D. Pewter

Question 138

Coating a metal with a thin, protective layer of another metal that resists corrosion can be achieved through which three specific processes?

A. Melting, boiling, and freezing

B. Tinning, galvanizing, and electroplating

C. Distillation, filtration, and evaporation

D. Oxidation, reduction, and neutralization

Question 139

In the tinning process, a clean iron sheet is:

A. Dipped in a bath of molten tin, then passed through hot rollers

B. Left exposed to open air with no further treatment

C. Coated only with paint

D. Melted down completely and reshaped

Question 140

Tin is specifically an effective coating for protecting iron in the tinning process mainly because:

A. Tin is very stable and resists corrosion effectively, forming a durable protective layer over the iron

B. Tin is highly reactive and corrodes quickly, protecting the iron by sacrificing itself

C. Tin is the cheapest metal available

D. Tin evaporates quickly, leaving no residue

🎯 How to get the most out of these questions

Attempt each question before revealing the answer.
Read the explanation even when you answered correctly — it reinforces the concept.
Note down any question you got wrong and revisit it the next day.
Use the pagination below the list to work through every page — do not stop at page 1.

📌 MCQs — FAQs

Are answers included for every question in this section?

Yes — each published question includes an answer. Explanations are shown where they have been added.

Can I print these questions?

Yes — use your browser's print option (Ctrl+P / Cmd+P) to print or save the page as PDF.

How often are questions updated?

New questions are added regularly. If a paper pattern changes, existing questions are reviewed and updated.