1.
Mole concept
Find the mass of 0.2 mol of CaCO₃. (Ca = 40, C = 12, O = 16)
Answer: C. Mass = moles × molar mass = 0.2 × 100 = 20 g.
WAEC SSCE Chemistry practice questions
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The WASSCE (May/June) is the West African Examinations Council's final exam for secondary school students. Each subject has an objective (multiple-choice) paper and a theory or essay paper.
- 866 questions in our bank
- 14 topics
- Every answer explained
10 free sample questions
Tap an answer to check it and see the explanation.
2.
Gas laws
A gas occupies 30 cm³ at a pressure of 700 mmHg. Find its volume at 250 mmHg, temperature remaining constant.
Answer: A. Boyle's law: P₁V₁ = P₂V₂, so V₂ = 700 × 30 ÷ 250 = 84 cm³.
3.
Solutions
Find the concentration of a solution containing 0.2 mol of solute in 200 cm³ of solution.
Answer: D. Concentration = moles ÷ volume in dm³ = 0.2 ÷ 0.2 = 1 mol/dm³.
4.
Electrolysis
A current of 2 A flows for 2 minutes. Find the quantity of electricity passed.
Answer: D. Q = It = 2 × (2 × 60) = 240 C (time must be in seconds).
5.
Acids, bases and salts
What is the pH of 0.1 mol/dm³ hydrochloric acid? (Assume it ionises completely.)
Answer: C. [H⁺] = 0.1 = 10⁻¹ mol/dm³, and pH = −log[H⁺] = 1.
6.
Chemical formulae
Calculate the percentage by mass of calcium in CaCO₃. (Ca = 40, C = 12, O = 16)
Answer: D. % of calcium = (mass of calcium in one formula unit ÷ molar mass) × 100 = 40%.
7.
Gases
A test for ammonia is that the gas
Answer: C. Ammonia turns damp red litmus paper blue.
8.
Organic chemistry
Which homologous series has the functional group –COOH (carboxyl)?
Answer: A. The functional group of alkanoic acids is –COOH (carboxyl).
9.
States of matter
A solid changing directly into a gas is called
Answer: C. Sublimation skips the liquid state, e.g. iodine crystals.
10.
Atomic structure
What is the atomic number of carbon?
Answer: B. Carbon has 6 protons, so its atomic number is 6.
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Questions in the MyGradePrep bank for each topic.
| Topic | Questions |
|---|---|
| Mole concept | 226 |
| Gas laws | 120 |
| Periodic table | 69 |
| Solutions | 67 |
| Atomic structure | 61 |
| States of matter | 61 |
| Electrolysis | 61 |
| Solubility | 60 |
| Chemical formulae | 40 |
| Organic chemistry | 38 |
| Acids, bases and salts | 18 |
| Redox | 18 |
| Gases | 14 |
| Separation techniques | 10 |