ZIMBABWE SCHOOL EXAMINATIONS COUNCIL General Certificate of Education Ordinary Level
**CHEMISTRY**
**PAPER 2 Theory**
**JUNE 2025 SESSION**
Additional materials: Electronic calculator Answer booklet Graph paper
INSTRUCTIONS TO CANDIDATES
Write your name, centre number and candidate number in the spaces at the top of this page and on all separate answer paper used. Answer all questions in Section A and any four from Section B. At the end of the examination, fasten any separate answer paper used securely to the question paper. Enter the numbers of Section B questions you have answered in the grid.
INFORMATION FOR CANDIDATES
The number of marks is given in brackets [ ] at the end of each question or part question.
A copy of the Periodic Table is printed on page 17.
| FOR EXAMINER'S USE | | | :--- | :--- | | Section A | | | Section B | | | | | | | | | | | | | | | TOTAL | |
**Section A**
Answer all questions from this section. Write your answers on the spaces provided in the question paper.
Question 1
(a)
Name the method used to separate a mixture of
1. sand and salt solution,
2. ethanol solution and water.
(b)
Table 1.1 is an incomplete table showing two ions and their subatomic particles.
**Table 1.1**
| ion | number of protons | number of electrons | | :---: | :---: | :---: | | \(N^{3-}\) | | | | \(H^{+}\) | | |
Complete Table 1.1 by stating the number of protons and electrons in each ion.
(c)
Draw a dot and cross diagram to show the bonding in ammonia.
Question 2
(a)
Fig 2.1 shows a zinc plate placed in copper sulphate solution.
Fig 2.1
#### (i)
Identify the brown solid deposited on the zinc plate.
#### (ii)
Write a balanced chemical equation for the chemical changes taking place.
#### (iii)
State the type of reaction which occurs when zinc is converted to the \(Zn^{2+}\) ions.
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(b)
Fig 2.2 represents a method used to test for a gas produced when calcium carbonate is heated.
Fig 2.2
#### (i)
Describe what happens when the calcium carbonate is heated.
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#### (ii)
State the acid base/base nature of the product that remains in the hard glass test tube.
Question 3
(a)
Define reduction in terms of
1. electron transfer,
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2. oxidation number.
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(b)
#### (i)
Fig 3.1 shows an energy profile for the conversion of **A** to **B**.
Fig 3.1
Name the type of energy represented by
1. \(x\),
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2. \(y\).
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#### (ii)
State, with a reason, whether the reaction is endothermic or exothermic.
(c)
Compare the reactivities of calcium and magnesium with water.
Question 4
(a)
Fig 4.1 shows how coal can be converted to other products during dry distillation.
Fig 4.1
#### (i)
Name substance X.
#### (ii)
State the role of the cold water.
#### (iii)
Explain the industrial importance of the process in value addition and beneficiation of coal.
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(b)
#### (i)
Fig 4.2 shows the structural formulae of compounds **A** and **B**.
Fig 4.2
Name compound
1. A,
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2. B.
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<img class="imgSvg" id = "mqpk0eie5ahytufein" src="https://ocr.unopasa.com/p/ocr_assets/46f9bd965d861a2557c0f73352bd3cc184f9dddcb2951848a6dda46e3c56b1c2.svg"/>
Fig 4.3
Describe a chemical test that can be used to distinguish between B and C.
Question 5
(a)
#### (i)
Define the term amphoteric.
#### (ii)
Two oxides \(XO_{3}\) and \(MO\) react with water according to the following equations:
$$ \begin{aligned} & MO_{(s)} + H_2O_{(l)} \rightarrow M^{2+}_{(aq)} + 2OH^{-}_{(aq)} \\ & XO_{3(g)} + H_2O_{(l)} \rightarrow 2H^{+}_{(aq)} + XO_4^{2-}_{(aq)} \end{aligned} $$
Identify the acid base/nature of
1. \(MO_{(s)}\),
2. \(XO_{3(g)}\).
(b)
Fig 5.1 shows a section of terylene.
Fig 5.1
#### (i)
State the type of polymerisation that formed terylene.
#### (ii)
Name the linkage in terylene.
#### (iii)
Draw the structures of the monomers of terylene.
#### (iv)
State any one use of terylene.
**Section B**
Answer any four questions from this section. Write your answer on the separate paper provided.
Question 6
(a)
In the electrolysis of acidified water, oxygen and hydrogen are produced.
#### (i)
Calculate the volume of hydrogen produced if \(50 cm^3\) of oxygen is produced at room temperature and pressure.
#### (ii)
Explain why the method of electrolysis is an expensive method of producing oxygen.
(b)
Hydrogen is used in the production of copper from copper (II) oxide according to the chemical equation shown.
$$ CuO_{(s)} + H_{2(g)} \rightarrow Cu_{(s)} + H_2O_{(g)} $$
#### (i)
Calculate the volume of hydrogen required at r.t.p to produce 1.6 g of copper.
#### (ii)
State and explain the role of hydrogen in the reaction.
(c)
Water samples from sources **A** and **B** were analysed. The results are shown in Table 6.1.
**Table 6.1**
| water source | test(s) | observation | | :---: | :--- | :--- | | A | heated for a few minutes | a white precipitate | | B | heated for a few minutes | no observable change |
#### (i)
Suggest an explanation for the differences in the observations.
#### (ii)
State any two advantages of drinking water from source **A**.
Question 7
(a)
#### (i)
The electronic configuration of an element, Y, is 2.8.2.
Give the molecular formula of the compound formed when Y reacts with chlorine.
#### (ii)
Explain why the compound formed when Y reacts with chlorine
1. conducts electricity when in molten form,
2. has a high boiling point,
3. is soluble in water.
(b)
Fig 7.1 shows a flow chart for the production of sulphuric acid.
Fig 7.1
Explain why
#### (i)
a temperature of \(450^\circ C\) is used in the converter,
#### (ii)
sulphur trioxide is not directly dissolved in water,
#### (iii)
a pressure of 1 atmosphere is used.