Preparing for the Cambridge IGCSE Chemistry exam requires practicing real exam-style questions. Below are 10 solved Chemistry questions covering core topics like diffusion, acids and bases, chemical bonding, and energy changes. Each one has multiple-choice options, worked-out solutions, and correct answers.

Question 1: Diffusion

Q1. A purple crystal is dropped into water. After some hours, the water becomes evenly purple. Which process is responsible?
A) Melting
B) Diffusion
C) Evaporation
D) Condensation

Solution:
The particles spread out from high concentration (crystal) to low concentration (water).
This is diffusion, a physical and reversible process.
Correct Answer: B (Diffusion).

Question 2: States of Matter

Q2. Which of the following best describes particles in a gas?
A) Closely packed, vibrating in fixed positions
B) Arranged in layers, sliding over each other
C) Far apart, moving freely in all directions
D) Tightly packed, unable to move

Solution:
Gas particles are far apart and move freely.
Correct Answer: C.

Question 3: Acids and Bases

Q3. Which equation represents the neutralisation of nitric acid with sodium hydroxide?
A) NaOH(aq) + HNO₃(aq) → NaNO₃(aq) + H₂O(l)
B) NaOH(aq) + HNO₃(aq) → NaNO₃(l) + H₂O(l)
C) NaOH(l) + HNO₃(l) → NaNO₃(l) + H₂O(aq)
D) NaOH(l) + HNO₃(aq) → NaNO₃(aq) + H₂(g)

Solution:
Acid + Alkali → Salt + Water.
Correct equation: NaOH(aq) + HNO₃(aq) → NaNO₃(aq) + H₂O(l).
Correct Answer: A.

Question 4: Exothermic Reactions

Q4. Which statement about neutralisation is correct?
A) The reaction rate increases during the reaction
B) The reaction is endothermic
C) The reaction transfers thermal energy to the surroundings
D) The temperature of the surroundings decreases

Solution:
Neutralisation is exothermic, releasing heat to surroundings.
Correct Answer: C.

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Question 5: Oxides

Q5. Which pair shows an acidic oxide and a basic oxide?
A) CO₂ and Na₂O
B) SO₂ and CO
C) NO₂ and H₂O
D) O₂ and Cl₂

Solution:
CO₂ is acidic, Na₂O is basic.
Correct Answer: A.

Question 6: Periodic Table

Q6. Which statements about trends across a Period are correct?

1. Aluminium is more metallic than sodium.
2. Beryllium is more metallic than carbon.
3. Boron is more metallic than lithium.
4. Magnesium is more metallic than silicon.

A) 1 and 2
B) 1 and 3
C) 2 and 4
D) 3 and 4

Solution:
Metallic character decreases across a period.
Correct comparisons: (2) Be > C, (4) Mg > Si.
Correct Answer: C (2 and 4).

Question 7: Compounds and Mixtures

Q7. Brass is an example of a:
A) Compound
B) Mixture
C) Element
D) Alloy

Solution:
Brass = Copper + Zinc (an alloy, which is a mixture).
Correct Answer: B (Mixture).

Question 8: Fuels

Q8. Hydrogen fuel cells produce electricity by combining hydrogen with:
A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Helium

Solution:
Hydrogen + Oxygen → Water + Energy.
Correct Answer: B (Oxygen).

Question 9: Radioactivity

Q9. Which instrument detects radioactive emissions?
A) Thermometer
B) Geiger–Müller counter
C) Barometer
D) Hygrometer

Solution:
Radioactivity is detected by a Geiger–Müller counter.
Correct Answer: B.

Question 10: Radiation

Q10. Which type of radiation is most penetrating?
A) Alpha
B) Beta
C) Gamma
D) X-rays

Solution:
Gamma rays have the highest penetrating power.
Correct Answer: C (Gamma).

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Conclusion

These 10 solved IGCSE Chemistry questions cover key topics: diffusion, acids and bases, neutralisation, oxides, the Periodic Table, alloys, fuel cells, and radiation. By studying these, students will gain both accuracy and exam confidence ahead of the 2025 IGCSE Chemistry paper.

Keywords

• IGCSE Chemistry 2025 questions
• solved IGCSE Chemistry past questions
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Credit: Allschool, Allcbt

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