Corrosion & Prevention — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Corrosion & Prevention MCQs with step-by-step solutions (8 questions). Part of Metals & Non-Metals. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Corrosion & Prevention · medium · theory
The rusting of iron requires the presence of both:
A. only dry air
B. only water
C. oxygen (air) and moisture (water) ✓ Correct
D. oxygen and nitrogen
Solution: Iron rusts only when both air (oxygen) and water/moisture are present.
Q2 — Corrosion & Prevention · hard · theory
Rust is chemically:
A. iron chloride
B. pure iron
C. hydrated iron(III) oxide ✓ Correct
D. iron sulphide
Solution: Rust is hydrated iron(III) oxide, Fe₂O₃·xH₂O.
Q3 — Corrosion & Prevention · medium · theory
The process of coating iron with a layer of zinc to prevent rusting is called:
A. galvanisation ✓ Correct
B. annealing
C. tempering
D. electrolysis
Solution: Galvanisation coats iron with zinc, which protects it from rusting.
Q4 — Corrosion & Prevention · medium · theory
Which of the following is NOT a method of preventing rusting?
A. Oiling and greasing
B. Galvanising
C. Painting
D. Adding salt to water ✓ Correct
Solution: Salt water actually speeds up rusting; painting, oiling and galvanising prevent it.
Q5 — Corrosion & Prevention · hard · theory
The green coating that forms on copper articles exposed to moist air is mainly:
A. copper chloride
B. iron oxide
C. basic copper carbonate ✓ Correct
D. copper sulphide
Solution: Copper corrodes to form a green layer of basic copper carbonate.
Q6 — Corrosion & Prevention · medium · theory
Stainless steel does not rust because it is an alloy of iron with:
A. copper and tin
B. carbon only
C. zinc and lead
D. chromium and nickel ✓ Correct
Solution: Adding chromium and nickel makes steel resistant to corrosion (stainless steel).
Q7 — Corrosion & Prevention · hard · theory
The black coating that dulls silver articles over time is due to the formation of:
A. silver oxide only
B. silver chloride
C. silver sulphide ✓ Correct
D. rust
Solution: Silver reacts with sulphur compounds in the air to form black silver sulphide (tarnish).
Q8 — Corrosion & Prevention · hard · theory
Iron objects rust faster near the sea because the moist air there contains:
A. no oxygen
B. no moisture
C. dissolved salts, which speed up corrosion ✓ Correct
D. only pure water
Solution: Salt-laden coastal air accelerates the electrochemical process of rusting.