Which of the following is an amphoteric oxide?
- A.Sodium oxide
- B.Aluminium oxide
- C.Carbon dioxide
- D.Sulphur dioxide
Correct answer
Explanation
The correct answer is B, aluminium oxide. An amphoteric oxide reacts with both acids and bases to form salts, and aluminium oxide does exactly that, behaving as a base towards hydrochloric acid and as an acid towards sodium hydroxide; zinc oxide is the other amphoteric oxide asked in examinations. Option A, sodium oxide, is a typical metal oxide and therefore basic, dissolving in water to give sodium hydroxide, a strong alkali. Option C, carbon dioxide, is a non-metal oxide and therefore acidic, dissolving in water to give carbonic acid, which is why it turns moist blue litmus red. Option D, sulphur dioxide, is likewise acidic and gives sulphurous acid in water. Remember the rule and its two exceptions: metal oxides are basic, non-metal oxides are acidic, and the oxides of aluminium and zinc are amphoteric.
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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