New Curriculum Third Term Chemistry examination for SS 1

Class: SSS 1
Term: Third Term
Subject: Chemistry
Time: 1 hour 30 minutes
Total Marks: 70

SECTION A: OBJECTIVES (40 MARKS)
Instruction: Answer ALL 40 questions. Each carries 1 mark.

1. A neutral carbon atom has electronic arrangement ________. (a) 4,4   (b) 2,4   (c) 2,8   (d) 2,6
2. Which of these behaviours is NOT evidence that a substance is hygroscopic? (a) It may be used to control moisture in storage   (b) It can absorb water vapour from air   (c) It gains mass in humid conditions   (d) It repels all moisture and remains completely unaffected in humid air
3. The main reason staff should understand safe chemical handling in a business is ________. (a) to protect workers, customers and product quality   (b) to avoid recording material quantities   (c) to guarantee that no product will ever change   (d) to eliminate the need for packaging
4. A student uses identical volumes of acid and alkali but does not know their concentrations. Why is neutralisation not guaranteed? (a) All acids and bases have equal reacting valencies   (b) Equal volumes imply equal concentrations   (c) The reacting amounts depend on concentration and stoichiometry   (d) The colour intensity of the indicator fixes stoichiometry
5. At the same conditions, gases X and Y have molecular masses 4 and 16. According to Graham’s law, how do their diffusion rates compare? (a) twice as fast   (b) equal in every case   (c) four times as fast   (d) half as fast
6. Why must a treatment plan for turbid water distinguish suspended particles from dissolved contaminants? (a) boiling always removes all dissolved chemical contaminants   (b) filtration removes many suspended particles but may not remove dissolved substances   (c) filtration alone removes every dissolved salt   (d) settling automatically disinfects the water
7. Which activity best integrates chemical knowledge with entrepreneurship? (a) Selecting packaging without checking chemical compatibility   (b) Setting a price without testing the formulation   (c) Selecting raw materials and quality checks for a safe detergent formulation   (d) Reducing raw-material costs without identity or safety checks
8. For a gas at constant pressure, which graph is most consistent with Charles' law when temperature is in kelvin? (a) An inverse curve of V against T   (b) A straight line through the origin on a V–T graph   (c) A vertical line at constant volume   (d) A horizontal V–T line for all temperatures
9. Carbon-12 has atomic number 6 and mass number 12. How many protons and neutrons are present? (a) 6 and 6   (b) 12 and 12   (c) 12 and 6   (d) 6 and 12
10. The ________ of a common acid added to an alkali can be demonstrated by an appropriate indicator colour change. (a) condensation   (b) sublimation   (c) neutralisation   (d) electrolysis
11. A salt absorbs atmospheric moisture until it dissolves in the water absorbed. It is described as ________. (a) efflorescent   (b) deliquescent   (c) sublimed   (d) insoluble
12. A gas has a molar volume of 22.4 dm³ at the stated conditions. What volume corresponds to 0.5 mol? (a) 44.8 dm³   (b) 5.6 dm³   (c) 22.4 dm³   (d) 11.2 dm³
13. The main reason an indicator is useful in acid-base titration is ________. (a) it increases the number of protons in every atom   (b) it prevents all heat changes   (c) it turns any mixture into pure water   (d) it gives a visible signal near the reaction's end point
14. Which of these is NOT a reasonable property of a covalently bonded carbon compound in general? (a) It must conduct electricity like a metal in every state   (b) Its behaviour depends on structure   (c) It may exist as molecules   (d) Its atoms share electron pairs
15. The main reason distilled water is preferred in certain quantitative experiments is ________. (a) it always has more minerals than tap water   (b) it changes every acid into a base   (c) it minimises interference from dissolved impurities   (d) it contains more living organisms
16. A trainee reports that soap batches vary in consistency even though the recipe is unchanged. Which improvement is most useful? (a) Stop checking completed products   (b) Measure ingredients and process conditions consistently, then compare batch records   (c) Change several ingredients without recording them   (d) Ignore variation until complaints increase
17. Using Avogadro constant 6.02 × 10²³ mol⁻¹, how many molecules are present in 0.25 mol? (a) 1.505 × 10²³   (b) 2.408 × 10²⁴   (c) 2.408 × 10²³   (d) 6.02 × 10²³
18. How should a laboratory temperature of −23°C be expressed on the approximate kelvin scale? (a) 250 K   (b) 310 K   (c) −250 K   (d) 296 K
19. A laboratory spill is suspected to be strongly alkaline. Which step is most defensible? (a) Add concentrated acid without checking the material   (b) Identify the substance and follow the labelled spill-response procedure   (c) Smell the spill to estimate its pH   (d) Wipe it with bare hands and resume work
20. Which molecular formula correctly represents ordinary water? (a) HO₂   (b) H₂O₂   (c) H₃O₂   (d) H₂O
21. A small chemical-products venture prices its liquid soap at ₦1,500 per unit. If material and packaging cost ₦950 per unit, its gross contribution before other costs is ________. (a) ₦450   (b) ₦2,450   (c) ₦950   (d) ₦550
22. All of these conclusions agree with kinetic theory of gases except ________. (a) gas particles are motionless at room temperature   (b) particles continually move   (c) temperature affects average kinetic energy   (d) collisions influence pressure
23. Which observation is strongest evidence of suspended impurities rather than dissolved ions? (a) Electrical conduction by a clear solution   (b) A change in pH without turbidity   (c) No visible solids after standing   (d) Visible particles settling on standing
24. ________ is a molecular characteristic chiefly responsible for the unusual solvent behaviour of water. (a) absence of oxygen   (b) lack of intermolecular forces   (c) metallic bonding in ice   (d) polarity
25. The correct sequence for evaluating a chemistry-related product idea is ________. (a) sell untested stock → ask customers what it contains → prepare a label   (b) identify need → assess safety and materials → estimate costs → produce trial batch → evaluate quality   (c) buy unknown raw materials → mix at random → discard trial records   (d) produce large stock → set any price → identify hazards → choose materials
26. Before producing a chemical consumer product for sale, which feasibility and safety checks should a venture perform? (a) assess demand, formulation safety, costs and legal requirements   (b) promise that all chemicals are harmless   (c) manufacture without evaluating risks   (d) discard product labels to reduce packaging cost
27. A laboratory filters a water sample but remains concerned about disease-causing microorganisms. The most appropriate additional consideration is ________. (a) measuring turbidity without any microbial control   (b) settling the already filtered sample without disinfection   (c) a suitable disinfection step   (d) filtration through finer paper as the only added step
28. Two solutions have pH values of 3 and 5. Which comparison of their acidity is justified? (a) necessarily twice as concentrated in all respects   (b) more acidic   (c) more alkaline   (d) neutral
29. A proposed soap venture compares two suppliers: Supplier A offers a cheaper unlabelled ingredient; Supplier B supplies traceable, specified material at slightly higher cost. The stronger professional decision is ________. (a) choose the unlabelled material solely because it is cheaper   (b) omit all quality records   (c) mix both materials without identification   (d) choose traceable material that meets the required specification and safety checks
30. A laboratory liquid shows the freezing and boiling behaviour expected for water under controlled conditions. What can this evidence help assess? (a) the shape of the measuring table   (b) the number of nearby trees   (c) its identity and degree of purity   (d) the speed of the laboratory clock
31. The ability of carbon to form multiple stable covalent bonds is explained chiefly by its ________. (a) lack of valence electrons   (b) charge of +4 on every carbon atom   (c) valency of four   (d) permanent ionic bond to itself
32. All of these are relevant chemistry-enterprise records except ________. (a) a register of unrelated football results   (b) product quality and safety observations   (c) raw-material costs   (d) batch quantities and dates
33. Which of the following equations best exemplifies the preparation of a salt by neutralisation? (a) C + O₂ → CO₂   (b) HCl + NaOH → NaCl + H₂O   (c) CaCO₃ → CaO + CO₂   (d) 2H₂ + O₂ → 2H₂O
34. The volume of a fixed amount of ideal gas is halved at constant temperature. What happens to its pressure? (a) halve the pressure   (b) double the pressure   (c) quadruple the amount of gas   (d) keep pressure unchanged
35. A hydrated crystal loses water of crystallisation to dry air and becomes powdery. This is ________. (a) efflorescence   (b) neutralisation   (c) precipitation   (d) deliquescence
36. At constant pressure, a gas occupies 240 cm³ at 27°C. Its volume at 127°C is approximately ________. (a) 320 cm³   (b) 400 cm³   (c) 280 cm³   (d) 160 cm³
37. Which statement concerning water molecules is NOT correct? (a) Water molecules are electrically polar   (b) Intermolecular attraction contributes to water's properties   (c) Oxygen and hydrogen atoms are joined by metallic bonds   (d) Water contains two hydrogen atoms per molecule
38. A solution turns blue litmus red. The observation is evidence that it is ________. (a) neutral   (b) acidic   (c) alkaline   (d) necessarily a pure salt
39. Which pair of substances could reasonably produce sodium sulfate by neutralisation? (a) HNO₃ and Ca(OH)₂   (b) HCl and KOH   (c) CH₃COOH and NH₃   (d) H₂SO₄ and NaOH
40. A chemist needs to obtain pure crystals from a saturated solution. A suitable next step, depending on the substance's solubility behaviour, is ________. (a) adding sand until crystals disappear   (b) heating indefinitely until the substance decomposes   (c) filtering before any crystals form and discarding the filtrate   (d) controlled cooling or evaporation followed by collection of crystals

SECTION B: THEORY (30 MARKS)
Instruction: Answer Question 1 and any other TWO questions. Each question carries 10 marks.

Question 1
(a) A gas occupies 240 cm³ at 27°C and constant pressure. Calculate its volume at 127°C. (6 marks)
(b) Two gases have molecular masses 4 and 16. Determine their diffusion-rate ratio. (4 marks)

Question 2
(a) Calculate the volume of 0.75 mol of an ideal gas at conditions where molar volume is 22.4 dm³. (4 marks)
(b) Determine the number of particles in 0.25 mol given Avogadro constant 6.02×10²³ mol⁻¹. (4 marks)
(c) State one industrial application of controlling temperature or pressure in a gas process. (2 marks)

Question 3
(a) Explain the difference between a deliquescent and an efflorescent substance. (4 marks)
(b) A stream sample is turbid and may contain disease-causing microorganisms. Outline three suitable stages or checks in its treatment and monitoring. (6 marks)

Question 4
(a) A small soap business sells 80 units at ₦1,500 each; direct material and packaging cost is ₦950 per unit. Calculate total revenue and contribution before other costs. (6 marks)
(b) Describe two control measures that would prevent unsafe or inconsistent batches. (4 marks)

Objective Marking Scheme
Question 1 – ✅ (b) 2,4
Question 2 – ✅ (d) It repels all moisture and remains completely unaffected in humid air
Question 3 – ✅ (a) to protect workers, customers and product quality
Question 4 – ✅ (c) The reacting amounts depend on concentration and stoichiometry
Question 5 – ✅ (a) twice as fast
Question 6 – ✅ (b) filtration removes many suspended particles but may not remove dissolved substances
Question 7 – ✅ (c) Selecting raw materials and quality checks for a safe detergent formulation
Question 8 – ✅ (b) A straight line through the origin on a V–T graph
Question 9 – ✅ (a) 6 and 6
Question 10 – ✅ (c) neutralisation
Question 11 – ✅ (b) deliquescent
Question 12 – ✅ (d) 11.2 dm³
Question 13 – ✅ (d) it gives a visible signal near the reaction's end point
Question 14 – ✅ (a) It must conduct electricity like a metal in every state
Question 15 – ✅ (c) it minimises interference from dissolved impurities
Question 16 – ✅ (b) Measure ingredients and process conditions consistently, then compare batch records
Question 17 – ✅ (a) 1.505 × 10²³
Question 18 – ✅ (a) 250 K
Question 19 – ✅ (b) Identify the substance and follow the labelled spill-response procedure
Question 20 – ✅ (d) H₂O
Question 21 – ✅ (d) ₦550
Question 22 – ✅ (a) gas particles are motionless at room temperature
Question 23 – ✅ (d) Visible particles settling on standing
Question 24 – ✅ (d) polarity
Question 25 – ✅ (b) identify need → assess safety and materials → estimate costs → produce trial batch → evaluate quality
Question 26 – ✅ (a) assess demand, formulation safety, costs and legal requirements
Question 27 – ✅ (c) a suitable disinfection step
Question 28 – ✅ (b) more acidic
Question 29 – ✅ (d) choose traceable material that meets the required specification and safety checks
Question 30 – ✅ (c) its identity and degree of purity
Question 31 – ✅ (c) valency of four
Question 32 – ✅ (a) a register of unrelated football results
Question 33 – ✅ (b) HCl + NaOH → NaCl + H₂O
Question 34 – ✅ (b) double the pressure
Question 35 – ✅ (a) efflorescence
Question 36 – ✅ (a) 320 cm³
Question 37 – ✅ (c) Oxygen and hydrogen atoms are joined by metallic bonds
Question 38 – ✅ (b) acidic
Question 39 – ✅ (d) H₂SO₄ and NaOH
Question 40 – ✅ (d) controlled cooling or evaporation followed by collection of crystals

Theory Marking Scheme
Question 1
(a) T₁=300 K, T₂=400 K (2); Charles law V₁/T₁=V₂/T₂ (2); V₂=240×400/300=320 cm³ (2). [6 marks]
(b) Graham law r₁/r₂=√(16/4)=2 (2); lighter gas diffuses twice as fast (2). [4 marks]
Question 2
(a) V=0.75×22.4 =16.8 dm³ (4). [4 marks]
(b) 0.25×6.02×10²³ = 1.505×10²³ particles (4). [4 marks]
(c) For a relevant industrial gas processing example where temperature/pressure changes gas volume or reaction conditions (2). [2 marks]
Question 3
(a) Deliquescent absorbs moisture and can dissolve in it (2); efflorescent loses water of crystallisation to air (2). [4 marks]
(b) Any three explained (2 each): settling/coagulation where appropriate, filtration of suspended matter, suitable disinfection, testing/verification of water quality. Do not claim filtration removes all dissolved substances. [6 marks]
Question 4
(a) Revenue =80×1500=₦120,000 (2); per-unit contribution=₦550 (2); total contribution=₦44,000 (2). [6 marks]
(b) Any two (2 each): verified supplier specifications, measured formulation, batch record, quality/safety checks, labelled storage, compliance with safety guidance. [4 marks]