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Quiz Chapter 4: Reactivity of Metals

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

10 questions · plays in fullscreen

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 is the chemical reaction when dilute hydrochloric acid is added to marble chips?

  1. Calcium chloride + Water + Carbon dioxide
  2. Calcium oxide + Hydrogen gas
  3. Calcium sulfate + Carbon monoxide + Water
  4. Calcium hydride + Chlorine gas
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Answer: A

Marble chips (calcium carbonate) react with dilute acid to produce a soluble salt, water, and carbon dioxide gas.

2. Why is coke (carbon) added to the blast furnace during the industrial extraction of iron?

  1. To lower the melting point of silica sand
  2. To act as a catalyst for slag formation
  3. To produce carbon monoxide which acts as a reducing agent
  4. To prevent oxygen gas from entering the furnace
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Answer: C

Coke burns in oxygen to form $CO_2$, which further reacts with carbon to form carbon monoxide ($CO$), the primary reducing agent that converts hematite to molten iron.

3. 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: $2CuO + C ightarrow 2Cu + CO_2$.

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 method is used to extract highly reactive metals such as aluminium and sodium from their ores?

  1. Reduction using carbon in a blast furnace
  2. Electrolysis of molten ore
  3. Direct heating of ore in air
  4. Physical separation by washing
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Answer: B

Metals above Carbon in the reactivity series form very stable oxides and can only be extracted by electrolysis of their molten compounds.

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 of the following metals can be extracted from its oxide ore by reduction using carbon powder?

  1. Potassium
  2. Magnesium
  3. Tin
  4. Aluminium
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Answer: C

Tin ($Sn$) is situated below Carbon in the reactivity series, meaning Carbon can reduce tin oxide to tin metal.

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

  1. Between Potassium and Sodium
  2. Between Aluminium and Zinc
  3. Between Zinc and Iron
  4. Between Copper and Gold
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Answer: B

Carbon can reduce zinc oxide but cannot reduce aluminium oxide, placing Carbon between Aluminium and Zinc.

9. Which metal does NOT react or burn when heated strongly in the presence of oxygen gas?

  1. Zinc
  2. Iron
  3. Copper
  4. Gold
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Answer: D

Gold is extremely unreactive and does not react with oxygen gas even when subjected to intense heat.

10. In a blast furnace, why does molten slag float on top of molten iron at the base?

  1. Slag has a higher density than molten iron
  2. Slag is less dense than molten iron
  3. Slag is immiscible with carbon monoxide gas
  4. Slag is magnetic while iron is non-magnetic
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Answer: B

Molten slag ($CaSiO_3$) is less dense than molten iron, floating on top and forming a protective layer that prevents re-oxidation of iron.

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