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WAEC WASSCE Chemistry Questions
Practise chemistry (science) for the West African Senior School Certificate Examination: 10 multiple-choice questions, each with the correct answer and a worked explanation. Click an option to check it, or “New questions” for another set.
Chemistry practice
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Q1.Avogadro’s number is approximately:
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Answer: B — 6.022 × 10²³
One mole contains 6.022 × 10²³ particles.
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Q2.8 g of HCl (molar mass 36.5) is dissolved to make 1000 mL of solution. Find the molarity.
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Answer: C — 0.219 M
Moles = 8/36.5 = 0.219; molarity = moles ÷ litres = 0.219 ÷ 1 = 0.219 M.
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Q3.A solution with pH 3 is:
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Answer: A — Acidic
pH below 7 is acidic.
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Q4.What is the pH of a solution with [H⁺] = 10⁻⁶ mol/L?
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Answer: D — 6
pH = −log[H⁺] = −log(10⁻⁶) = 6.
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Q5.The chemical name of baking soda is:
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Answer: B — Sodium bicarbonate (sodium hydrogen carbonate)
Baking soda is NaHCO₃.
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Q6.4 g of glucose (molar mass 180) is dissolved to make 2000 mL of solution. Find the molarity.
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Answer: B — 0.011 M
Moles = 4/180 = 0.022; molarity = moles ÷ litres = 0.022 ÷ 2 = 0.011 M.
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Q7.The atomic number of an element equals the number of:
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Answer: D — Protons
Atomic number = number of protons in the nucleus.
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Q8.What is the mass of 2.5 mol of sodium chloride (NaCl)? (Molar mass 58.5 g/mol)
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Answer: B — 146.25 g
Mass = moles × molar mass = 2.5 × 58.5 g/mol = 146.25 g.
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Q9.Water has a maximum density at about:
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Answer: C — 4 °C
Water is densest at about 4 °C.
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Q10.What is the mass of 2 mol of carbon dioxide (CO₂)? (Molar mass 44 g/mol)
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Answer: B — 88 g
Mass = moles × molar mass = 2 × 44 g/mol = 88 g.
How to approach chemistry questions
Moles = mass ÷ molar mass; molarity = moles ÷ litres. pH = −log[H⁺] and pH + pOH = 14 at 25 °C. For concepts, link each property to its position in the periodic table.
About WAEC WASSCE
West African Senior School Certificate Examination — conducted by West African Examinations Council (WAEC). Senior school certificate exam taken in Nigeria, Ghana, Sierra Leone, Liberia and The Gambia.
Original practice questions written for this site in the style and difficulty of each exam’s syllabus. They are not past papers and the site is not affiliated with any exam body. Exam patterns, marking schemes and syllabi change — always check the latest official notification.
WAEC WASSCE practice topics
| Topic | Section | Question source |
|---|---|---|
| English Grammar | English | Question bank |
| Algebra | Mathematics | Calculated (new numbers every set) |
| Biology | Science | Question bank |
| Chemistry | Science | Calculated + question bank |