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Quiz Chapter 4: Reactivity of Metals

10 questions ยท Form 3 Science Bab 4: Reactivity of Metals

Question 1 of 10Score: 0

What chemical formula represents the main component of bauxite ore?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. What chemical formula represents the main component of bauxite ore?

  1. Fe_2O_3
  2. Al_2O_3
  3. PbS
  4. SnO_2
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Answer: B

Bauxite is the primary ore of aluminium and consists mainly of hydrated aluminium oxide ($Al_2O_3$).

2. What products are formed when calcium carbonate ($CaCO_3$) is heated strongly?

  1. Calcium metal and carbon dioxide
  2. Calcium oxide and carbon dioxide
  3. Calcium hydroxide and oxygen gas
  4. Calcium oxide and carbon monoxide
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Answer: B

Thermal decomposition of calcium carbonate yields solid calcium oxide (quicklime) and carbon dioxide gas: $CaCO_3 ightarrow CaO + CO_2$.

3. What term describes naturally occurring solid chemical elements or compounds found in Earth's crust?

  1. Plastics
  2. Minerals
  3. Polymers
  4. Synthetic compounds
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Answer: B

Minerals are inorganic elements or compounds found naturally with specific crystalline structures in the Earth's crust.

4. Predict what happens when dry hydrogen gas is passed over strongly heated aluminium oxide powder.

  1. Aluminium metal and water vapor are produced
  2. No reaction occurs because aluminium is more reactive than hydrogen
  3. Aluminium hydroxide powder forms immediately
  4. Explosive ignition creates carbon dioxide
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Answer: B

Aluminium lies higher than Hydrogen in the reactivity series, so Hydrogen is unable to reduce aluminium oxide.

5. Which metal burns with a brilliant bright white flame when reacting with oxygen?

  1. Copper
  2. Lead
  3. Magnesium
  4. Iron
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Answer: C

Magnesium reacts vigorously with oxygen when ignited, burning with an intensely bright white flame to form magnesium oxide.

6. Which of the following minerals exists in an uncombined elemental state in the Earth's crust?

  1. Hematite
  2. Bauxite
  3. Gold
  4. Cassiterite
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Answer: C

Gold is a very unreactive metal, so it exists naturally as a free element rather than as a chemical compound.

7. Which environmental impact is directly associated with roasting sulfide ores during metal extraction?

  1. Acid rain caused by sulfur dioxide emission
  2. Eutrophication of rivers caused by nitrates
  3. Ozone layer depletion caused by CFCs
  4. Thermal pollution causing algae blooms
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Answer: A

Roasting sulfide metal ores releases sulfur dioxide gas ($SO_2$), which dissolves in rainwater to form acid rain.

8. Where is Hydrogen positioned in the Reactivity Series of Metals?

  1. Between Aluminium and Carbon
  2. Between Zinc and Iron
  3. Between Iron and Lead
  4. Between Copper and Silver
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Answer: B

Dry hydrogen gas reduces iron oxide to iron when heated, but cannot reduce zinc oxide, placing Hydrogen between Zinc and Iron.

9. Predict the observation when carbon powder is strongly heated with copper(II) oxide powder.

  1. No reaction takes place; mixture remains black
  2. A brown solid is produced along with a gas that turns limewater cloudy
  3. The mixture melts into a bright yellow liquid with sparks
  4. White fumes are released leaving a blue residue
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Answer: B

Carbon is more reactive than copper, so it reduces black copper(II) oxide to brown copper metal, producing $CO_2$ gas: $2CuO + C ightarrow 2Cu + CO_2$.

10. Which reagent is used to confirm the presence of carbon dioxide gas emitted during a reaction?

  1. Acidified potassium manganate(VII)
  2. Limewater
  3. Litmus paper
  4. Anhydrous copper(II) sulfate
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Answer: B

Carbon dioxide gas reacts with clear limewater (calcium hydroxide) to produce insoluble calcium carbonate precipitate, making the limewater cloudy.

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