Mini practice paper: 8 questions
Mixed-difficulty questions from across the Chemistry syllabus. Tap "Show answer" after each to check yourself.
Q1 · Difficulty 1/3
What is the relative formula mass (Mr) of calcium carbonate, CaCO₃? [Ar: Ca = 40, C = 12, O = 16]
- 112
- 68
- 72
- 100
Show answer & explanation
✓ Answer: D — 100
Award 1 mark for correct calculation. Mr = 40 + 12 + (3 × 16) = 100. B is incorrect because it omits one oxygen atom (40 + 12 + 16 = 68). C is incorrect due to arithmetic error. A is incorrect because it counts oxygen atoms incorrectly as 4 instead of 3.
Q2 · Difficulty 1/3
A mixture of sand and salt is added to water and stirred. Which separation technique should be used first to separate the sand from the salt solution?
- chromatography
- crystallisation
- filtration
- distillation
Show answer & explanation
✓ Answer: C — filtration
Award 1 mark for selecting filtration. Sand is insoluble and remains as residue when the salt solution passes through filter paper. B is incorrect — crystallisation is used after filtration to obtain salt crystals from solution. D is incorrect — distillation separates liquids or obtains solvent from solution. A is incorrect — chromatography separates dissolved substances based on different solubilities.
Q3 · Difficulty 1/3
What is the value of Avogadro's constant?
- 6.02 × 10²² per mole
- 6.02 × 10²³ per mole
- 6.02 × 10⁻²³ per mole
- 6.02 × 10²⁴ per mole
Show answer & explanation
✓ Answer: B — 6.02 × 10²³ per mole
02 × 10²³ per mole. Award 1 mark for correct identification of Avogadro's constant. C is incorrect — this is the reciprocal with wrong power. D is incorrect — the power is 23, not 24. A is incorrect — the power is 23, not 22.
Q4 · Difficulty 2/3
A chemist in a pharmaceutical laboratory needs to prepare 0.25 mol of sodium hydroxide solution. What mass of sodium hydroxide must be dissolved?
[Ar: Na = 23, O = 16, H = 1]
- 4.0 g
- 10.0 g
- 16.0 g
- 40.0 g
Show answer & explanation
✓ Answer: B — 10.0 g
0 g. Award 1 mark for correct calculation. Mr of NaOH = 23 + 16 + 1 = 40. Mass = moles × Mr = 0.25 × 40 = 10.0 g. A is incorrect — this uses Mr = 16. C is incorrect — this uses Mr = 64. D is incorrect — this is the mass of 1 mole of NaOH.
Q5 · Difficulty 2/3
A company in Brazil produces hydrogen gas by the electrolysis of water. The equation for the reaction at the negative electrode is: 2H₂O + 2e⁻ → H₂ + 2OH⁻. What mass of hydrogen, in g, is produced when 4.8 dm³ of hydrogen gas is collected at r.t.p.? [Relative atomic mass: H = 1]
- 4.0
- 0.2
- 0.4
- 2.0
Show answer & explanation
✓ Answer: C — 0.4
4 g). Award 1 mark for correct answer. Number of moles = volume ÷ 24 = 4.8 ÷ 24 = 0.2 mol. Relative molecular mass of H₂ = 2. Mass = moles × Mr = 0.2 × 2 = 0.4 g. B is incorrect because this is the number of moles, not the mass. D is incorrect because this uses Mr of H₂ as 10. A is incorrect because this uses Mr of H₂ as 20.
Q6 · Difficulty 2/3
A researcher at an agricultural institute in Kenya analysed a sample of irrigation water. The water contained 0.0050 mol of dissolved calcium sulfate (CaSO₄) in 500 cm³.
What is the concentration of calcium sulfate in the water in mol/dm³?
- 0.0025 mol/dm³
- 0.010 mol/dm³
- 0.10 mol/dm³
- 2.5 mol/dm³
Show answer & explanation
✓ Answer: B — 0.010 mol/dm³
010 mol/dm³). Award 1 mark for correct calculation. 500 cm³ = 0.500 dm³. Concentration = moles ÷ volume = 0.0050 ÷ 0.500 = 0.010 mol/dm³. A is incorrect — this multiplies moles by volume instead of dividing. C is incorrect — this uses 50 cm³ instead of 500 cm³. D is incorrect — this divides 0.0050 by 0.002 instead of 0.500.
Q7 · Difficulty 1/3
A fertiliser company in Indonesia produces ammonium sulfate, (NH₄)₂SO₄, for agricultural use. What is the relative formula mass (Mr) of ammonium sulfate?
[Ar: N = 14, H = 1, S = 32, O = 16]
- 146
- 164
- 114
- 132
Show answer & explanation
✓ Answer: D — 132
Award 1 mark for correct calculation: (2 × 14) + (8 × 1) + 32 + (4 × 16) = 28 + 8 + 32 + 64 = 132. C is incorrect — this omits one nitrogen atom. A is incorrect — this adds an extra oxygen atom. B is incorrect — this counts 10 hydrogen atoms instead of 8.
Q8 · Difficulty 2/3
The Mr of NaCl (Na=23, Cl=35.5) is:
- 58.5
- 46
- 71
- 35.5
Show answer & explanation
✓ Answer: A — 58.5
23+35.5=58.5.
CIE IGCSE Chemistry FAQ
What does the CIE IGCSE Chemistry exam look like?
The CIE IGCSE Chemistry exam is structured across 3 components. Paper 1 (Multiple Choice): 40 multiple-choice questions, 1 mark each. 45 minutes. Tests breadth of knowledge. Paper 2 (Core) / Paper 4 (Extended): Structured written paper. 1 hour 30 minutes (Core) or 1 hour 45 minutes (Extended). Tests depth of understanding and application. Paper 6 (Alternative to Practical): Written paper assessing practical skills for candidates without lab access. 1 hour. Worth ~20% of the total. Total exam time: ~3 hours, depending on tier (Core vs Extended).
Can I download a free CIE IGCSE Chemistry past paper?
Real CIE past papers are published directly by CIE on their official website. Kramizo doesn't redistribute copyrighted past papers, but we do generate free AI-written practice papers in the exact same style — same command words, same difficulty tier, same mark conventions. Use this practice paper as warm-up, then time yourself on official past papers before exam day.
How is CIE IGCSE Chemistry graded?
Grades: A* (highest) to G (lowest), with U (ungraded). Most universities require C or above. Kramizo's practice questions are tagged with difficulty 1-3 mapping roughly to the lower, middle, and top grade boundaries you'll encounter in the real exam.