Form Four Chemistry pre-national papers
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Work through a pre-national paper under exam conditions, mark yourself with the marking guide, and use the result to decide what to revise before the national examination.
2026 Form Four Chemistry pre-national exam (032/1) — Lindi Region
Time: 3 hours · Section A: 16 marks · Section B: 54 marks · Section C: 30 marks
Instructions from the paper:
• This paper consists of sections A, B and C with a total of eleven (11) questions.
• Answer all questions in Sections A and B and two (2) questions from Section C.
• Section A carries 16 marks, Section B 54 marks and Section C 30 marks.
How to use this page: choose an option for each multiple-choice question and click “Check Answer”. A correct answer plays a short sound and shows an explanation; a wrong answer shows the right option and why. For the matching item and written questions, answer on paper first, then click “View Answer”.
SECTION A (16 marks): Question 1 — Multiple Choice (10 marks)
(i) Which set of laboratory apparatus is used for measuring volume?
(ii) The empirical formula of a compound is CH₃ and its molar mass is 30 g. Its molecular formula is:
(iii) To produce the greatest amount of hydrogen in a short time, 1 g of magnesium should react with:
(iv) Which group represents acidic oxides?
(v) Fractional distillation of a water–ethanol mixture is possible because:
(vi) What is the molarity of a solution containing 26.5 g anhydrous sodium carbonate in 5 dm³?
(vii) Brownian movement is taken as evidence of the:
(viii) An isotope of element X has atomic number Z and mass number A. The number of neutrons is:
(ix) C₂H₄Cl₂ can be represented by different structures which are called:
(x) The general term for a mixture of different metals is:
SECTION A continued: Question 2 — Matching Item (6 marks)
Match the effects of various chemicals in List A with the corresponding warning signs in List B. (6 marks)
| # | List A | Your answer |
|---|---|---|
| i | When poured on wool it completely damages the surface | |
| ii | When poured on a small fire it bursts and turns into a bigger fire | |
| iii | When brought near the skin, the person complains of itching | |
| iv | When exposed to air a sudden blast with light occurs | |
| v | When poured into food, a rat that eats it dies | |
| vi | Prolonged exposure damages body organs |
List B
- A. Toxic
- B. Radioactive materials
- C. Corrosive
- D. Flammable
- E. Oxidant
- F. Explosive
- G. Irritant
- H. Fragile
Correct matches (1 mark each): i-C, ii-E, iii-G, iv-F, v-A, vi-B
- i. Corrosive
- ii. Oxidant
- iii. Irritant
- iv. Explosive
- v. Toxic
- vi. Radioactive materials
SECTION B (54 marks): Questions 3–8
3. (a) Using three points, justify whether muddy water is a mixture or a compound.
(b) FeCl₃ is electrovalent and ionizes in water.
(i) How many moles of ions are formed when one mole is completely ionized?
(ii) How many ions are responsible for conduction (from one mole)?
Suggested answer and marking guide
(a) Muddy water is a mixture: components retain individual properties; can be separated by physical methods (filtration); composition is variable (3 marks).
(b)
- (i) FeCl₃ → Fe³⁺ + 3Cl⁻ → 4 moles of ions (2 marks)
- (ii) 4 × 6.02 × 10²³ = 2.408 × 10²⁴ ions (2 marks)
4. (a) Butanoic acid + ethanol:
(i) Chemical equation
(ii) IUPAC name of major product
(iii) Name of the reaction type
(b) Hydrocarbon 80 % C, 20 % H; vapour density 15.
(i) Empirical formula
(ii) Molecular formula
(iii) Family of hydrocarbon
Suggested answer and marking guide
(a)
- (i) CH₃CH₂CH₂COOH + CH₃CH₂OH ⇌ CH₃CH₂CH₂COOCH₂CH₃ + H₂O
- (ii) Ethyl butanoate
- (iii) Esterification (3 marks total)
(b)
- (i) C : H = 80/12 : 20/1 ≈ 6.67 : 20 → 1 : 3 → CH₃
- (ii) Empirical mass 15; molecular mass = 2 × 15 = 30 → C₂H₆
- (iii) Alkane family (5 marks)
5. (a) (i) State Le Chatelier’s principle.
(ii) Outline any six factors affecting rate of reaction.
(b) For 2SO₂ + O₂ ⇌ 2SO₃ ΔH = −94.9 kJ/mol, state the effect on equilibrium position of SO₃ if:
(i) pressure is raised
(ii) temperature is raised
(iii) SO₃ is removed
Suggested answer and marking guide
(a) (i) When a system at equilibrium is subjected to a change, the equilibrium shifts to oppose that change (2 marks). (ii) Concentration, temperature, surface area, catalyst, pressure (gases), nature of reactants (any six, 6 marks).
(b)
- (i) Shifts right (more SO₃) — fewer gas moles on product side
- (ii) Shifts left — forward reaction is exothermic
- (iii) Shifts right to replace removed SO₃ (3 marks)
6. (a) 1 kg maize ground to 1 kg flour — physical or chemical change? Give five reasons.
(b) Suggest separation methods for: (i) splint + water (ii) iodine + sand (iii) dyes (iv) muddy water
Suggested answer and marking guide
(a) Physical change. Reasons: no new substance; chemical composition unchanged; only particle size changes; flour retains chemical properties of maize; mass essentially conserved (5–6 marks).
(b) (i) Filtration (ii) Sublimation (iii) Chromatography (iv) Filtration (4 marks).
7. (a) Explain what happens when:
(i) Conc. H₂SO₄ is exposed to the atmosphere
(ii) A bottle of AgNO₃ is left open
(iii) Mouths of test tubes containing HCl(g) and NH₃(g) are brought together
(b) Explain with equations where necessary:
(i) Reaction of lead nitrate with dilute HCl stops immediately
(ii) Zn reacts with dilute HCl but Cu does not
(iii) Burning Mg continues in CO₂
Suggested answer and marking guide
(a)
- (i) Hygroscopic — absorbs moisture and becomes dilute
- (ii) Photosensitive — decomposes to metallic silver (darkens)
- (iii) White smoke of NH₄Cl forms: HCl + NH₃ → NH₄Cl (3 marks)
(b)
- (i) Insoluble PbCl₂ coating stops further reaction: Pb(NO₃)₂ + 2HCl → PbCl₂ + 2HNO₃
- (ii) Zn above H in reactivity series; Cu below H
- (iii) 2Mg + CO₂ → 2MgO + C (Mg reduces CO₂) (6 marks)
8. (a) Define: (i) Cracking (ii) Isomerism (iii) Homologous series
(b) Write structures of: (i) 2,2-dichloro-3-methylpentane (ii) 4-ethyl-2,6-dimethylheptane (iii) Pentan-1-ol
Suggested answer and marking guide
(a) Cracking — breaking large hydrocarbons into smaller useful ones by heat (often with catalyst). Isomerism — same molecular formula, different structures. Homologous series — family with same functional group/general formula, successive members differ by CH₂ (3 marks).
(b) Correct open structural formulae for the three named compounds (6 marks).
SECTION C (30 marks): Answer any two questions
9. (a) 25 cm³ of Na₂CO₃·xH₂O (7.15 g in 250 cm³) required 20 cm³ of 0.25 M HCl. Find x.
(b) 90 g Zn reacted with HCl; 17.5 g remained. How many moles of HCl reacted?
Suggested answer and marking guide
(a) n(HCl) = 0.25 × 0.020 = 0.005 mol. From Na₂CO₃ + 2HCl → …, n(Na₂CO₃) in 25 cm³ = 0.0025 mol. In 250 cm³ = 0.025 mol. M = 7.15/0.025 = 286. Anhydrous = 106 → water mass 180 → x = 10. Salt = Na₂CO₃·10H₂O (8–9 marks).
(b) Mass Zn reacted = 72.5 g; n(Zn) = 72.5/65 ≈ 1.115 mol; n(HCl) = 2 × 1.115 ≈ 2.23 mol (3–4 marks).
10. Describe any six ways of softening hard water.
Suggested answer and marking guide (≈15 marks)
Any six (≈2 marks each): boiling (temporary hardness); washing soda; lime; ion-exchange resins; zeolite/permutit; distillation.
11. (a) With a labelled diagram and balanced equation, describe the preparation of chlorine from MnO₂ and concentrated HCl.
(b) Why must the gas be collected in a fume chamber?
(c) State the method used and give a reason.
Suggested answer and marking guide
(a) MnO₂ + 4HCl(conc.) → MnCl₂ + 2H₂O + Cl₂. Labelled apparatus: thistle funnel → reaction flask (MnO₂ + conc. HCl) → washing/drying → collection (upward displacement of air or as appropriate). Warm gently (8–9 marks).
(b) Chlorine is poisonous and irritating; the fume chamber removes the hazardous gas (2 marks).
(c) Chemical displacement / redox method — MnO₂ oxidises Cl⁻ from HCl to Cl₂ while itself is reduced (2 marks).
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Get Form Four Chemistry pre-national exams on Google Play Back to all secondary examsFrequently asked questions: Form 4 Chemistry pre-national exams
What is a Form Four pre-national exam?
A pre-national exam is a practice paper set close to the national examination. It lets you rehearse the real paper format, test your timing and find the topics that still need revision.
Which Form Four Chemistry pre-national exam is free on this page?
The free paper is the Lindi Region 2026 Form Four Chemistry paper (presented here as a pre-national practice paper). Other regional and year papers are on the Click Online Academy app.
How do I use the interactive paper?
Choose an option for each multiple-choice question and click Check Answer to see whether you are right and why. For the matching item and written questions, answer on paper first, then click View Answer to see the marking guide.
How many questions must I answer?
Answer all questions in Sections A and B, and any two of the three questions in Section C. The paper has eleven questions in total and lasts three hours.