Galvanisation is the process of coating iron or steel with a layer of:
- A.Tin
- B.Zinc
- C.Chromium
- D.Nickel
Correct answer
Explanation
The correct answer is B, zinc. In galvanisation iron or steel is given a coating of zinc, usually by dipping it in the molten metal, and the coating protects the iron in two ways: it keeps out air and moisture, and because zinc is more reactive than iron it corrodes in place of the iron even where the coating has been scratched. Option A, tin, is used to coat steel in the tinplate of food cans, a process called tinning, which protects only while the coating is intact. Option C, chromium, is applied by electroplating for shine and corrosion resistance and is also alloyed into stainless steel along with nickel. Option D, nickel, is likewise an electroplating and alloying metal. Recall that rusting needs both oxygen and moisture, so a coating, paint, oil or grease that keeps either away prevents it.
Read the full article: Metals and Non-Metals: Properties, Ores and Alloys
Practice Questions
View allCalamine is an ore of:
- A.Tin
- B.Magnesium
- C.Zinc
- D.Copper
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Calamine is zinc carbonate, and since it is a carbonate ore it is converted to the oxide by calcination, that is by heating in the absence of air, before being reduced to the metal.
Read the full explanation →Which of the following is NOT an alloy?
- A.Solder
- B.Silver
- C.Bronze
- D.Brass
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Silver is an element, a pure metal with its own place in the periodic table, so it cannot be an alloy; an alloy is a homogeneous mixture of two or more metals, or of a metal with a non-metal such as carbon.
Read the full explanation →Which of the following is the most ductile metal?
- A.Gold
- B.Copper
- C.Silver
- D.Iron
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Ductility is the property of being drawn into a wire, and gold is the most ductile metal known; it is also the most malleable, so a very small quantity can be beaten into an extremely thin sheet or drawn into a very long wire.
Read the full explanation →Brass is an alloy of:
- A.copper and tin
- B.copper and nickel
- C.copper and iron
- D.copper and zinc
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Brass takes the workability of copper and the hardness of zinc, resists corrosion and is easy to cast, which is why it is used for utensils, locks, taps, fittings and wind instruments.
Read the full explanation →Which metal is in the liquid state at room temperature?
- A.Sodium
- B.Mercury
- C.Lead
- D.Tungsten
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Mercury is the only metal that is liquid at ordinary room temperature, which is why it was long used in thermometers and barometers; it is also the metal that forms amalgams, alloys in which mercury is one component.
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