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ACT Chemistry Questions
Practise chemistry (science) for the ACT: 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.Which bond is formed by the sharing of electrons?
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Answer: A — Covalent
Covalent bonds share electron pairs.
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Q2.What is the mass of 2 mol of carbon dioxide (CO₂)? (Molar mass 44 g/mol)
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Answer: C — 88 g
Mass = moles × molar mass = 2 × 44 g/mol = 88 g.
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Q3.The main component of natural gas is:
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Answer: B — Methane
Methane (CH₄).
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Q4.What is the pH of a solution with [H⁺] = 10⁻¹ mol/L?
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Answer: C — 1
pH = −log[H⁺] = −log(10⁻¹) = 1.
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Q5.The process of converting a solid directly into a gas is called:
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Answer: D — Sublimation
Sublimation, e.g. dry ice or naphthalene.
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Q6.What is the mass of 3 mol of methane (CH₄)? (Molar mass 16 g/mol)
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Answer: B — 48 g
Mass = moles × molar mass = 3 × 16 g/mol = 48 g.
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Q7.Which gas is produced when zinc reacts with dilute hydrochloric acid?
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Answer: B — Hydrogen
Zn + 2HCl → ZnCl₂ + H₂.
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Q8.8 g of glucose (molar mass 180) is dissolved to make 1000 mL of solution. Find the molarity.
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Answer: B — 0.044 M
Moles = 8/180 = 0.044; molarity = moles ÷ litres = 0.044 ÷ 1 = 0.044 M.
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Q9.Rusting of iron requires:
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Answer: D — Both oxygen and water
Iron rusts in the presence of oxygen and moisture, forming hydrated iron(III) oxide.
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Q10.What is the pH of a solution with [OH⁻] = 10⁻² mol/L at 25 °C?
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Answer: B — 12
[OH⁻] = 10⁻² → pOH = 2; pH = 14 − 2 = 12 (at 25 °C).
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 ACT
ACT — conducted by ACT, Inc.. US college admission test with English, Math and Reading, plus an optional Science section.
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.
ACT practice topics
| Topic | Section | Question source |
|---|---|---|
| Algebra | Mathematics | Calculated (new numbers every set) |
| Geometry & Mensuration | Mathematics | Calculated (new numbers every set) |
| Probability & Combinatorics | Mathematics | Calculated (new numbers every set) |
| English Grammar | English | Question bank |
| Physics | Science | Calculated + question bank |
| Chemistry | Science | Calculated + question bank |