Home / iGCSE Chemistry (0620) Theory (Core):9.4 Reactivity series: Exam Style Questions Paper 3

iGCSE Chemistry (0620) Theory (Core):9.4 Reactivity series: Exam Style Questions Paper 3- New Syllabus

iGCSE Chemistry Theory (Core) Paper 3 - All Chapters

Question

This question is about metals.
(a) Iron is extracted from its ore using carbon in a blast furnace.
When calcium carbonate is heated strongly in the blast furnace, it forms calcium oxide and carbon dioxide.
\( \mathrm{CaCO}_3 \rightarrow \mathrm{CaO} + \mathrm{CO}_2 \)
(i) State the type of reaction that occurs when calcium carbonate is heated strongly.
(ii) State whether calcium oxide is an acidic oxide or a basic oxide.
Explain your answer.
(iii) Name the gas removed by calcium oxide in flue gas desulfurisation.
(b) Zinc is also extracted from its ore using carbon.
(i) The equation for the extraction of zinc from zinc oxide is shown:
\( 2\mathrm{ZnO} + \mathrm{C} \rightarrow 2\mathrm{Zn} + \mathrm{CO}_2 \)
Explain how this equation shows that zinc oxide is reduced.
(ii) Brass is an alloy that contains zinc.
Name the other metal in brass.
(iii) Suggest two reasons why brass is used to make water taps rather than pure zinc.
(c) The extraction of zinc from its ore produces atmospheric sulfur dioxide and carbon dioxide.
(i) State the adverse effect that increased levels of sulfur dioxide have on the environment.
(ii) Increased levels of carbon dioxide in the atmosphere can lead to increased global warming.
State one strategy which would help to remove carbon dioxide that is already in the atmosphere.
(d) Table 6.1 shows the observations when four different metals are added separately to dilute hydrochloric acid.
Put the four metals in order of their reactivity.
Put the least reactive metal first.

Most-appropriate topic codes (Cambridge IGCSE Chemistry 0620):

• Topic 9.6 — Extraction of metals (Parts (a)(i), (a)(ii), (a)(iii), (b)(i), (b)(iii))
• Topic 9.3 — Alloys and their properties (Part (b)(ii), (b)(iii))
• Topic 10.3 — Air quality and climate (Parts (c)(i), (c)(ii))
• Topic 9.4 — Reactivity series (Part (d))

▶️ Answer/Explanation

(a)(i)
(Thermal) decomposition

Thermal decomposition is a reaction where a single substance breaks down into two or more simpler substances upon heating. \( \mathrm{CaCO}_3 \) decomposes into \( \mathrm{CaO} \) and \( \mathrm{CO}_2 \).

(a)(ii)
Basic AND metal oxide.

Calcium oxide is a metal oxide (formed from a metallic element and oxygen). Metal oxides generally act as bases and react with acids to form salts and water.

(a)(iii)
Sulfur dioxide

Flue gas desulfurisation involves spraying calcium oxide (or calcium carbonate) into waste gases. It reacts with acidic sulfur dioxide to remove it before it is released into the atmosphere.

(b)(i)
The zinc oxide loses oxygen.

Reduction is defined as the loss of oxygen. In the equation, \( \mathrm{ZnO} \) loses its oxygen to form zinc (\( \mathrm{Zn} \)), so it has been reduced.

(b)(ii)
Copper

Brass is a common alloy consisting of a mixture of copper and zinc.

(b)(iii)
Any 2 from: hard(er) / strong(er) / more resistant to corrosion.

Pure zinc is relatively weak and reactive. Alloying zinc with copper to form brass creates a material that is stronger, harder, and much more resistant to corrosion, making it ideal for water taps.

(c)(i)
Acid rain

Sulfur dioxide dissolves in atmospheric water droplets to form sulfuric acid, leading to acid rain that damages buildings, aquatic life, and vegetation.

(c)(ii)
Planting trees

Trees and other plants absorb carbon dioxide from the atmosphere for photosynthesis, acting as a carbon sink and helping to remove the gas already present.

(d)
W → Fe → Mg → Ba

Based on the observations in Table 6.1, ‘W’ shows no reaction (least reactive). ‘Fe’ shows a very slow reaction. ‘Mg’ shows a quick reaction. ‘Ba’ shows a very rapid reaction (most reactive). This order corresponds to reactivity based on bubble and temperature rate.

More iGCSE Chemistry Theory (Core) Paper 3 ...........
Scroll to Top