New Curriculum First Term Chemistry examination for SS 1

Class: SSS 1
Term: First 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 small laboratory makes liquid soap in limited batches, while a plant produces thousands of litres daily. The clearest difference is ________. (a) whether safety rules apply   (b) whether matter is chemically involved   (c) scale of production   (d) whether products require raw materials
2. Which activity is NOT a direct application of chemical knowledge? (a) Identifying safe chemical preservatives   (b) Analysing the acidity of soil   (c) Selecting an appropriate cleaning agent   (d) Preparing a factory wage ledger without analysing chemical materials
3. The part of the scientific method that tests a stated prediction using repeatable observations is ________. (a) an unsupported conclusion   (b) a change of research title   (c) a controlled experiment   (d) a personal preference
4. A compound has empirical formula CH₂ and molar mass 42 g mol⁻¹ (C=12, H=1). Which molecular formula follows? (a) C₃H₆   (b) CH₂   (c) C₄H₈   (d) C₂H₄
5. Fish deaths are reported below an industrial discharge point. Which industrial response yields testable evidence and controls further harm? (a) moving warning signs downstream without investigation   (b) adding dye so the polluted water looks clean   (c) increasing discharge at night   (d) testing the effluent and water, then controlling discharge to standards
6. A worker must transfer a corrosive solution. Protective goggles are primarily intended to reduce ________. (a) wear of the measuring cylinder scale   (b) evaporation of the solution   (c) injury from splashes to the eyes   (d) change in solution concentration
7. ________ represents an element by an internationally agreed symbol rather than its full name. (a) Na for sodium   (b) S for sodium   (c) So for sodium   (d) N for sodium
8. Which of the following research problems best illustrates organic chemistry rather than inorganic chemistry? (a) Examining the reactions of a carbon-containing hydrocarbon   (b) Measuring the conductivity of molten sodium chloride   (c) Classifying mineral ores by metal content   (d) Comparing the crystal structures of common salts
9. A health worker applies chemistry to drinking-water treatment. Which action most directly demonstrates its usefulness? (a) Selecting the storage material without chemical compatibility checks   (b) Comparing water samples by appearance without testing   (c) Measuring the volume of water without identifying impurities   (d) Selecting a suitable process to remove or destroy contaminants
10. Which observation indicates that evaporation, rather than filtration alone, is needed to recover a dissolved solid? (a) The mixture contains visible stones   (b) The solute passes through the filter with its solvent   (c) A coarse solid remains on the paper   (d) The filter is folded into a cone
11. A bottle labelled 'corrosive' is found leaking near a bench. Which response is most responsible? (a) Smell the liquid directly to verify the label   (b) Keep others away and alert the teacher or trained supervisor for controlled cleanup   (c) Mix it immediately with an unknown substance   (d) Pick it up barehanded to identify its contents
12. The effect of toxic substances on stream water is studied together with cleanup measures. Which branch of chemistry has the closest focus? (a) organic chemistry focused on structure determination   (b) analytical chemistry focused only on concentration measurement   (c) environmental chemistry   (d) industrial chemistry focused on manufacturing yield
13. A manufacturer's input is limestone and its output is cement. The classification 'building-materials industry' is based mainly on ________. (a) chemical identity of the starting compound   (b) end use of the manufactured product   (c) distance to the raw-material quarry   (d) size of the production plant
14. For separating a mixture of two soluble salts with markedly different temperature-dependent solubilities, an appropriate method is ________. (a) simple sieving of dissolved ions   (b) ordinary filtration alone   (c) magnetic separation of the solution   (d) fractional crystallisation
15. Vegetation near a factory’s untreated acidic discharge has deteriorated. Which chemical hazard most plausibly explains the change? (a) chemical contamination of receiving soil and water   (b) mechanical soil compaction unrelated to the effluent   (c) variation in rainfall without contaminant transport   (d) a temporary increase in stream temperature without chemical discharge
16. A flammable reagent is left near an ignition source. Which correction should the teacher require? (a) move it to an approved closed storage location away from ignition   (b) place the container closer to the flame for visibility   (c) remove all hazard labels   (d) add water to every solvent container
17. Using valencies Na = 1 and O = 2, the formula of the oxide formed is ________. (a) NaO₂   (b) Na₂O₂   (c) NaO   (d) Na₂O
18. A hypothesis predicts that warming increases the rate at which sugar dissolves. Which experimental comparison provides the strongest evidence? (a) One warm cup stirred and one cold cup left unstirred   (b) Equal sugar masses and water volumes at different measured temperatures   (c) Different sugar masses in different water volumes at one temperature   (d) Two cups with different sugar sizes and different stirring rates
19. When heating a liquid in a test tube, which precaution reduces the risk of hot liquid ejecting toward someone? (a) hold the heated glass directly with bare hands   (b) point its mouth away from people and heat gently   (c) look straight into the mouth during boiling   (d) seal the tube tightly before heating
20. The first twenty elements include magnesium and aluminium. Their correct symbols are ________. (a) Ma and Au   (b) Ms and Ad   (c) Mn and Am   (d) Mg and Al
21. A grower chooses between fertilizers with different nutrient analyses. Which use of chemical knowledge is involved? (a) determine land boundaries by sight   (b) measure the height of farm buildings   (c) relate material composition to agricultural purpose   (d) predict tomorrow's rainfall without data
22. An atom has 11 protons and 12 neutrons. Its atomic and mass numbers respectively are ________. (a) 11 and 23   (b) 12 and 23   (c) 11 and 12   (d) 23 and 11
23. A factory converts imported inputs into packaged detergents. Which classification basis best describes the factory? (a) the heat released during a single reaction step   (b) the nature of its products and processing activities   (c) the purity of imported sodium hydroxide   (d) the elemental composition of one detergent sample
24. All of these may present chemical-laboratory hazards except ________. (a) an unlabelled reagent   (b) a flammable solvent beside a flame   (c) an open container of corrosive solution   (d) a correctly labelled empty record folder
25. A formula contains two hydrogen atoms and one oxygen atom per molecule. Its correct representation is ________. (a) H₂O₂   (b) H₂O   (c) HO₂   (d) H₃O
26. Why is chemistry directly relevant to the manufacture and performance of soap? (a) soap properties and manufacture depend on chemical materials and reactions   (b) soap cleans exclusively through physical abrasion   (c) soap depends only on water evaporation   (d) soap contains no chemically manufactured ingredients
27. A laboratory investigates energy changes and reaction rates in chemical systems. Its work is most closely related to ________. (a) analytical chemistry   (b) organic chemistry   (c) environmental chemistry   (d) physical chemistry
28. Which basis is appropriate for classifying chemical industries? (a) Only the state of matter of a single product   (b) Scale of operation and types of products   (c) Only the molecular mass of one raw material   (d) Only the chemical composition of the building paint
29. The appropriate action for leftover laboratory chemicals is to ________. (a) mix unknown leftovers in a single bottle   (b) pour all liquids into the nearest drain   (c) follow the designated, labelled waste-disposal procedure   (d) return contaminated chemicals to stock jars
30. All of the following strengthen the credibility of a chemical investigation except ________. (a) comparing results with a hypothesis   (b) discarding measurements that disagree with the expected outcome   (c) recording experimental conditions   (d) repeating observations
31. Which statement correctly distinguishes a chemical equation from a formula? (a) A formula always includes reaction conditions; an equation never does   (b) Both are measurements of liquid volume only   (c) An equation shows reactants and products; a formula shows composition of a substance   (d) An equation is a list of apparatus; a formula records temperature only
32. A mixture contains sand and dissolved salt. To recover dry salt without sand, the most suitable sequence is ________. (a) filter to remove sand, then evaporate the filtrate   (b) add more sand and decant the liquid   (c) evaporate the mixture first and discard all residue   (d) filter and retain only the sand
33. Which of these practices is NOT a sound rule for handling chemical reagents? (a) Avoiding direct inhalation of vapours   (b) Reading hazard instructions before use   (c) Using labelled containers   (d) Returning unused portions to the original stock bottle without checking contamination
34. The main reason unknown chemicals must not be tasted is ________. (a) their containers may be heavy   (b) their toxicity or corrosiveness may be uncertain   (c) their names may be long   (d) their colour may change when exposed to air
35. All of these are responsible chemical-industry practices except ________. (a) training workers to handle chemicals   (b) using appropriate pollution-control systems   (c) releasing untreated hazardous waste into public drains   (d) monitoring waste streams
36. A colourless liquid is assumed to be pure water. What additional observation would most reliably test the claim? (a) change the observation to match the hypothesis   (b) ignore any result that contradicts the claim   (c) test a measurable property such as boiling point under controlled conditions   (d) record the colour as sufficient proof of purity
37. The main difference between industrial and analytical approaches in chemistry is that industrial chemistry emphasises ________. (a) qualitative and quantitative chemical analysis   (b) analysis of the identity and quantity of substances   (c) laboratory measurement of composition   (d) large-scale manufacture and process improvement
38. Which equation is correctly balanced for the formation of water? (a) 2H₂ + 2O₂ → H₂O   (b) H₂ + 2O₂ → 2H₂O   (c) H₂ + O₂ → H₂O   (d) 2H₂ + O₂ → 2H₂O
39. The ________ from a filtration experiment is the liquid that passes through the filter paper. (a) precipitate   (b) filtrate   (c) crystal lattice   (d) residue
40. Which proposal best combines industrial value with environmental protection? (a) Increase output by bypassing waste controls   (b) Discharge acidic waste without monitoring   (c) Provide jobs while treating waste before release   (d) Reduce costs by dumping residues into streams

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

Question 1
(a) A pupil claims that every colourless liquid is pure water. Formulate a testable hypothesis and explain one controlled test. (5 marks)
(b) State two reasons why repeating the measurement improves confidence in a conclusion. (5 marks)

Question 2
(a) A detergent factory provides employment but its effluent damages a stream. Explain two industrial benefits and two environmental control responses. (8 marks)
(b) Name one appropriate chemistry branch for analysing the polluted water. (2 marks)

Question 3
(a) A dry mixture contains 20 g sand and 10 g soluble salt. Describe an appropriate sequence for recovering both substances. (6 marks)
(b) Explain why filtering the mixture without adding solvent cannot separate the fine salt entirely. (4 marks)

Question 4
(a) For an atom containing 11 protons, 12 neutrons and 11 electrons, state its atomic number, mass number and charge. (4 marks)
(b) Write a balanced equation for formation of water from hydrogen and oxygen, then calculate the molecular formula when empirical formula CH₂ has mass 42 (C=12, H=1). (6 marks)

Objective Marking Scheme
Question 1 – ✅ (c) scale of production
Question 2 – ✅ (d) Preparing a factory wage ledger without analysing chemical materials
Question 3 – ✅ (c) a controlled experiment
Question 4 – ✅ (a) C₃H₆
Question 5 – ✅ (d) testing the effluent and water, then controlling discharge to standards
Question 6 – ✅ (c) injury from splashes to the eyes
Question 7 – ✅ (a) Na for sodium
Question 8 – ✅ (a) Examining the reactions of a carbon-containing hydrocarbon
Question 9 – ✅ (d) Selecting a suitable process to remove or destroy contaminants
Question 10 – ✅ (b) The solute passes through the filter with its solvent
Question 11 – ✅ (b) Keep others away and alert the teacher or trained supervisor for controlled cleanup
Question 12 – ✅ (c) environmental chemistry
Question 13 – ✅ (b) end use of the manufactured product
Question 14 – ✅ (d) fractional crystallisation
Question 15 – ✅ (a) chemical contamination of receiving soil and water
Question 16 – ✅ (a) move it to an approved closed storage location away from ignition
Question 17 – ✅ (d) Na₂O
Question 18 – ✅ (b) Equal sugar masses and water volumes at different measured temperatures
Question 19 – ✅ (b) point its mouth away from people and heat gently
Question 20 – ✅ (d) Mg and Al
Question 21 – ✅ (c) relate material composition to agricultural purpose
Question 22 – ✅ (a) 11 and 23
Question 23 – ✅ (b) the nature of its products and processing activities
Question 24 – ✅ (d) a correctly labelled empty record folder
Question 25 – ✅ (b) H₂O
Question 26 – ✅ (a) soap properties and manufacture depend on chemical materials and reactions
Question 27 – ✅ (d) physical chemistry
Question 28 – ✅ (b) Scale of operation and types of products
Question 29 – ✅ (c) follow the designated, labelled waste-disposal procedure
Question 30 – ✅ (b) discarding measurements that disagree with the expected outcome
Question 31 – ✅ (c) An equation shows reactants and products; a formula shows composition of a substance
Question 32 – ✅ (a) filter to remove sand, then evaporate the filtrate
Question 33 – ✅ (d) Returning unused portions to the original stock bottle without checking contamination
Question 34 – ✅ (b) their toxicity or corrosiveness may be uncertain
Question 35 – ✅ (c) releasing untreated hazardous waste into public drains
Question 36 – ✅ (c) test a measurable property such as boiling point under controlled conditions
Question 37 – ✅ (d) large-scale manufacture and process improvement
Question 38 – ✅ (d) 2H₂ + O₂ → 2H₂O
Question 39 – ✅ (b) filtrate
Question 40 – ✅ (c) Provide jobs while treating waste before release

Theory Marking Scheme
Question 1
(a) Hypothesis relates specific test outcome to water purity (2); appropriate measure e.g., fixed-pressure boiling point / temperature and control (2); record and compare observed evidence (1). [5 marks]
(b) Repetition detects anomalous results (2), reveals reproducibility (2), permits averaging where suitable (1). [5 marks]
Question 2
(a) Benefits e.g. jobs, useful products, raw material market (2 marks each ×2=4); effluent treatment/monitoring, safe waste handling, environmental compliance (2 each ×2=4). [8 marks]
(b) Environmental chemistry (2). [2 marks]
Question 3
(a) Add solvent and dissolve salt (1); filter to retain sand (2); wash/dry recovered sand (1); evaporate/crystallise filtrate for salt (2). [6 marks]
(b) Both constituents are solids (2); suitable solvent selectively dissolves salt so filtration can retain sand (2). [4 marks]
Question 4
(a) Atomic number 11 (1), mass number 23 (2), neutral charge (1). [4 marks]
(b) 2H₂ + O₂ → 2H₂O (3); CH₂ empirical mass = 14, factor 42/14=3, molecular formula C₃H₆ (3). [6 marks]