100+ Free AS-Level Chemistry Practice Questions

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A reaction with theoretical yield 12.5 g produced 9.4 g of product. What is the percentage yield to 3 significant figures?

133%

3.10%

94.0%

75.2%

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AS-Level Physics

Practice Questions100 questions

2026 Statistics

Key Facts: AS-Level Chemistry Exam

A-E

Grading scale (no A*)

AQA AS Chemistry 7404 scheme of assessment

2 papers

1h 30m, 80 marks each (AQA 7404)

AQA 7404 specification

15%

Minimum marks linked to practical skills

Ofqual subject content for AS Chemistry

20%

Minimum marks assessing Level 2+ maths skills

Ofqual subject content for AS Chemistry

AS-Level Chemistry (AQA 7404 / Edexcel 8CH0 / OCR H032) is the Year 12 standalone qualification covering Physical, Inorganic and Organic Chemistry. Two written papers, A-E grading (no A*), with at least 15% practical and 20% mathematical content on 2026 specifications.

Sample AS-Level Chemistry Practice Questions

Try these sample questions to test your AS-Level Chemistry exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which subatomic particle has a relative mass of approximately 1 and a charge of 0?

A.Neutron

B.Proton

C.Electron

D.Positron

Explanation: Neutrons have a relative mass of 1 and no charge. Protons share the same mass but carry +1, while electrons have a relative mass of 1/1836 (effectively negligible) and a charge of -1.

2A sample of chlorine contains 75% Cl-35 and 25% Cl-37. What is the relative atomic mass to 2 decimal places?

A.35.50

B.36.00

C.35.00

D.37.00

Explanation: RAM = (75 x 35 + 25 x 37) / 100 = (2625 + 925) / 100 = 3550 / 100 = 35.50. The weighted mean accounts for the relative abundances of each isotope.

3In time-of-flight (TOF) mass spectrometry, why are ions accelerated by an electric field before reaching the flight tube?

A.So that ions of the same charge gain the same kinetic energy, allowing m/z to be derived from flight time

B.To ionise the sample by knocking off electrons

C.To separate ions by colour as they pass through the field

D.To slow heavier ions so they ionise more efficiently

Explanation: All ions with the same charge gain the same kinetic energy (KE = qV) from the accelerating field. Since KE = 1/2 mv^2, lighter ions move faster and reach the detector sooner, so flight time is a direct measure of m/z.

4Which electron configuration represents a ground-state nickel atom (Ni, Z = 28)?

A.1s2 2s2 2p6 3s2 3p6 3d8 4s2

B.1s2 2s2 2p6 3s2 3p6 4s2 3d10

C.1s2 2s2 2p6 3s2 3p6 3d10

D.1s2 2s2 2p6 3s2 3p6 4s2 4p6

Explanation: Nickel has 28 electrons. 4s fills before 3d, but once both are occupied 3d is written before 4s in shell-by-shell order: 1s2 2s2 2p6 3s2 3p6 3d8 4s2. The 3d subshell holds 8 of the remaining 10 electrons after 4s is filled.

5Across Period 3 from Na to Ar, the first ionisation energy generally increases. Which element shows a DROP from the previous element due to electron-pair repulsion in a 3p orbital?

A.Sulfur (S)

B.Magnesium (Mg)

C.Aluminium (Al)

D.Silicon (Si)

Explanation: S has the configuration [Ne]3s2 3p4. The fourth 3p electron pairs with another in the same orbital, and electron-pair repulsion makes it easier to remove, so S has a slightly LOWER first ionisation energy than P. This is direct evidence for sub-shells.

6How many particles are present in 0.250 mol of CO2? (Avogadro constant = 6.022 x 10^23 mol^-1)

A.1.51 x 10^23

B.6.02 x 10^23

C.2.41 x 10^24

D.1.51 x 10^22

Explanation: Number of particles = moles x NA = 0.250 x 6.022 x 10^23 = 1.51 x 10^23 molecules of CO2. Each CO2 molecule contains 3 atoms in total, but the question asks for particles (molecules).

7A 4.40 g sample of CO2 occupies what volume at 298 K and 100 kPa? (R = 8.31 J K^-1 mol^-1)

A.2.48 x 10^-3 m^3

B.24.8 m^3

C.2.48 m^3

D.248 m^3

Explanation: Moles of CO2 = 4.40 / 44.0 = 0.100 mol. Using pV = nRT in SI units: V = nRT / p = (0.100 x 8.31 x 298) / 100000 = 247.6 / 100000 = 2.48 x 10^-3 m^3 (about 2.48 dm^3).

8A reaction with theoretical yield 12.5 g produced 9.4 g of product. What is the percentage yield to 3 significant figures?

A.75.2%

B.133%

C.3.10%

D.94.0%

Explanation: Percentage yield = (actual / theoretical) x 100 = (9.4 / 12.5) x 100 = 75.2%. Yield is always less than or equal to 100% in practice due to incomplete reactions, side reactions and losses in transfer.

9What is the atom economy for producing ethanol via hydration of ethene: C2H4 + H2O -> C2H5OH?

A.100%

B.62.5%

C.50.0%

D.78.3%

Explanation: Atom economy = (Mr of desired product / sum of Mr of all products) x 100. Here ethanol is the only product, so atom economy is 100%. Addition reactions inherently have 100% atom economy because no by-product forms.

1025.0 cm^3 of 0.100 mol dm^-3 NaOH is exactly neutralised by 20.0 cm^3 of HCl. What is the concentration of the HCl?

A.0.125 mol dm^-3

B.0.0800 mol dm^-3

C.0.200 mol dm^-3

D.0.500 mol dm^-3

Explanation: Moles NaOH = 0.0250 x 0.100 = 2.50 x 10^-3 mol. NaOH + HCl react 1:1 so moles HCl = 2.50 x 10^-3 mol. Concentration HCl = 2.50 x 10^-3 / 0.0200 = 0.125 mol dm^-3.

About the AS-Level Chemistry Exam

AS-Level Chemistry is a standalone Year 12 qualification covering the first half of full A-Level Chemistry content. The course is divided into Physical, Inorganic and Organic Chemistry with a strong practical and mathematical skills component. AQA 7404 is assessed via two 1h 30m papers (80 marks each); Edexcel 8CH0 uses two 1h 45m papers; OCR H032 has two papers covering breadth and depth of knowledge.

Questions

100 scored questions

Time Limit

3 hours total (2 x 1h 30m papers, AQA 7404)

Passing Score

Grade E is the minimum pass; AS grades A-E (no A*)

Exam Fee

GBP 50-100 per subject (school-set entry fee) (AQA, Edexcel (Pearson), OCR)

AS-Level Chemistry Exam Content Outline

~25%

Physical Chemistry

Atomic structure (subatomic particles, mass spectrometry, ionisation energy, electron configuration), amount of substance (mole, Avogadro constant, pV=nRT, titration, atom economy), bonding (ionic, covalent, metallic, intermolecular forces, VSEPR shapes), energetics (Hess's law, calorimetry q=mc deltaT, bond enthalpy), kinetics (collision theory, Maxwell-Boltzmann, catalysts), equilibria (Le Chatelier, Kc), oxidation and reduction (oxidation numbers, half-equations)

~30%

Inorganic Chemistry

Periodicity of Period 3 (atomic radius, ionisation energy, melting point Na to Ar, conductivity), Group 2 alkaline earth metals (reactivity trend, hydroxide and sulfate solubility, uses of Ca(OH)2, Mg(OH)2 and BaSO4), Group 7 halogens (colour, displacement, oxidising power, halide tests with AgNO3 and NH3, disproportionation, chlorine in water treatment), introduction to transition elements (variable oxidation states, coloured complexes, catalysis)

~35%

Organic Chemistry

Introduction (IUPAC nomenclature, structural and skeletal formulae, structural and E/Z isomerism, mechanism types), alkanes (cracking, combustion, free radical substitution, pollutants), alkenes (electrophilic addition, Markovnikov, addition polymerisation), haloalkanes (nucleophilic substitution SN1/SN2, hydrolysis, elimination, CFCs), alcohols (oxidation with K2Cr2O7, fermentation vs hydration, dehydration), organic analysis (Tollens', Fehling's, bromine water, mass spectrometry M+ peak, infrared spectroscopy O-H, C=O, C-H, N-H)

~10%

Practical and Skills

Titration with burette, pipette and conical flask; end point vs equivalence; recrystallisation; reflux; simple and fractional distillation; thin-layer chromatography and Rf calculation; safety hazards and risk assessment; uncertainty and significant figures in measurement

How to Pass the AS-Level Chemistry Exam

What You Need to Know

Passing score: Grade E is the minimum pass; AS grades A-E (no A*)
Exam length: 100 questions
Time limit: 3 hours total (2 x 1h 30m papers, AQA 7404)
Exam fee: GBP 50-100 per subject (school-set entry fee)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

AS-Level Chemistry Study Tips from Top Performers

1Learn the bonding shapes (VSEPR) and bond angles by heart: linear 180, trigonal planar 120, tetrahedral 109.5, trigonal bipyramidal 90/120, octahedral 90 - lone pairs reduce the angle by ~2.5 each

2Master the mole triangle and pV=nRT in SI units (Pa, m^3, K) - mixing kPa or dm^3 without converting is the most common calculation error

3Use a flowchart for organic mechanisms (free radical substitution, electrophilic addition, nucleophilic substitution SN1 vs SN2) - examiners reward the correct curly arrows from lone pair or bond to electrophile

4Practise halide tests in order: AgNO3 gives white/cream/yellow precipitate, then NH3 (dilute then concentrated) confirms Cl/Br/I - this is a guaranteed exam question every year

Frequently Asked Questions

What is the difference between AS-Level and A-Level Chemistry?

AS-Level Chemistry covers only the Year 12 content (about half of full A-Level). It is a standalone qualification that does NOT count toward the final A-Level grade since the 2017 reform. Students who sit AS receive an AS certificate graded A-E.

How many papers does AS-Level Chemistry have?

AQA 7404 has two 1 hour 30 minute papers worth 80 marks each. Edexcel 8CH0 has two 1 hour 45 minute papers worth 80 marks each. OCR H032 has two papers: Breadth in Chemistry and Depth in Chemistry. All boards include short-answer, structured-response and multiple-choice questions; a calculator and data booklet are permitted.

Is AS-Level Chemistry graded A*-E?

No. AS-Level grades range from A to E only; there is no A* grade at AS. Full A-Levels are graded A*-E. The AQA scheme of assessment confirms AS Chemistry is graded on a five-point A-E scale.

How much practical and mathematical content is assessed?

At least 15% of marks assess knowledge and understanding linked to practical work, and at least 20% of marks assess Level 2 or higher mathematical skills (titration calculations, mole arithmetic, Hess cycles, pV=nRT, Rf values, uncertainty). There is no separate practical exam at AS, but practical skills are assessed in the written papers.