AQA AS Level Chemistry Paper 1 LATEST 2025 WITH
QUESTIONS AND CORRECT VERIFIED ANSWERS GRADED A+
GUARANTEED PASS
SECTION A — Multiple Choice / Short Response (1–2
marks)
1. Q: What is the electronic configuration of Al³⁺?
A: 1s² 2s² 2p⁶
Rationale: Aluminium (Z =13) loses three electrons → configuration same as neon.
2. Q: An element has 2,8,5 electrons. Which group is it in?
A: Group 15.
Rationale: Five electrons in the outer shell → group 15.
3. Q: How many protons are in ²⁷Al?
A: 13.
Rationale: Atomic number of Al = 13.
4. Q: Which block of the periodic table contains S and Cl?
A: p-block.
Rationale: Both end in p orbital electrons.
5. Q: What type of bond is in Cl₂?
A: Covalent.
Rationale: Non-metals share electrons.
6. Q: What is the oxidation number of Mn in MnO₄⁻?
A: +7.
Rationale: 4×(–2) + x = –1 → x = +7.
7. Q: What is the general formula of an alkene?
A: CₙH₂ₙ.
Rationale: Alkenes are unsaturated hydrocarbons with one double bond.
8. Q: Which gas turns limewater milky?
A: CO₂.
Rationale: Forms CaCO₃ precipitate.
9. Q: Is NaCl soluble in water?
A: Yes.
Rationale: Ionic lattice dissolves due to hydration energy.
10. Q: What type of reaction: Mg + 2HCl → MgCl₂ + H₂?
A: Redox & acid–metal.
Rationale: Mg oxidised, H⁺ reduced.
11. Q: What is the molarity of 1 mol in 2 dm³?
A: 0.5 mol dm⁻³.
Rationale: moles ÷ volume.
12. Q: Which particle has a mass number of 1 and charge 0?
A: Neutron.
Rationale: Proton has charge +1.
, 13. Q: What is the main intermolecular force between CO₂ molecules?
A: London forces.
Rationale: Non-polar molecule.
14. Q: What is the pH of a neutral solution at 25°C?
A: 7.
Rationale: [H⁺] = 1×10⁻⁷ mol dm⁻³.
15. Q: Which reagent distinguishes aldehydes from ketones?
A: Tollen’s reagent.
Rationale: Aldehydes are oxidised to acids.
SECTION B — Calculations and Explanations (2–4 marks)
16. Q: Calculate relative atomic mass of chlorine from isotopes ³⁵Cl (75%) and ³⁷Cl (25%).
A: 35.5.
Rationale: (0.75×35 + 0.25×37).
17. Q: % yield of 50 g product from 60 g theoretical?
A: ~83.3%.
Rationale: (50÷60×100).
18. Q: What volume of H₂ at STP from 2 g Mg + excess HCl?
A: 0.0496 m³ / 49.6 dm³.
Rationale: Mg + 2HCl → H₂; 2 g Mg = 0.0825 mol H₂; 0.0825×24 = ~1.98 dm³
(approx).
19. Q: Empirical formula from 40% C, 6.7% H, 53.3% O?
A: CH₂O.
Rationale: Convert to moles, divide by smallest.
20. Q: Calculate concentration if 5 g NaOH in 500 cm³.
A: 0.25 mol dm⁻³.
Rationale: moles = 5/40=0.125; 0.125/0.5.
21. Q: Ionisation energy trend from Na to Mg?
A: Increases.
Rationale: More nuclear charge same shell.
22. Q: Why does atomic radius decrease across a period?
A: Increased nuclear charge pulls electrons closer.
23. Q: Why does Mg react faster with acid than Zn?
A: More reactive → lower ionisation energy.
24. Q: What is the lattice energy trend of MgO vs NaCl?
A: MgO > NaCl.
Rationale: Higher charges.
25. Q: Draw shape of NH₃.
A: Trigonal pyramidal.
Rationale: 3 bonds, 1 lone pair.
QUESTIONS AND CORRECT VERIFIED ANSWERS GRADED A+
GUARANTEED PASS
SECTION A — Multiple Choice / Short Response (1–2
marks)
1. Q: What is the electronic configuration of Al³⁺?
A: 1s² 2s² 2p⁶
Rationale: Aluminium (Z =13) loses three electrons → configuration same as neon.
2. Q: An element has 2,8,5 electrons. Which group is it in?
A: Group 15.
Rationale: Five electrons in the outer shell → group 15.
3. Q: How many protons are in ²⁷Al?
A: 13.
Rationale: Atomic number of Al = 13.
4. Q: Which block of the periodic table contains S and Cl?
A: p-block.
Rationale: Both end in p orbital electrons.
5. Q: What type of bond is in Cl₂?
A: Covalent.
Rationale: Non-metals share electrons.
6. Q: What is the oxidation number of Mn in MnO₄⁻?
A: +7.
Rationale: 4×(–2) + x = –1 → x = +7.
7. Q: What is the general formula of an alkene?
A: CₙH₂ₙ.
Rationale: Alkenes are unsaturated hydrocarbons with one double bond.
8. Q: Which gas turns limewater milky?
A: CO₂.
Rationale: Forms CaCO₃ precipitate.
9. Q: Is NaCl soluble in water?
A: Yes.
Rationale: Ionic lattice dissolves due to hydration energy.
10. Q: What type of reaction: Mg + 2HCl → MgCl₂ + H₂?
A: Redox & acid–metal.
Rationale: Mg oxidised, H⁺ reduced.
11. Q: What is the molarity of 1 mol in 2 dm³?
A: 0.5 mol dm⁻³.
Rationale: moles ÷ volume.
12. Q: Which particle has a mass number of 1 and charge 0?
A: Neutron.
Rationale: Proton has charge +1.
, 13. Q: What is the main intermolecular force between CO₂ molecules?
A: London forces.
Rationale: Non-polar molecule.
14. Q: What is the pH of a neutral solution at 25°C?
A: 7.
Rationale: [H⁺] = 1×10⁻⁷ mol dm⁻³.
15. Q: Which reagent distinguishes aldehydes from ketones?
A: Tollen’s reagent.
Rationale: Aldehydes are oxidised to acids.
SECTION B — Calculations and Explanations (2–4 marks)
16. Q: Calculate relative atomic mass of chlorine from isotopes ³⁵Cl (75%) and ³⁷Cl (25%).
A: 35.5.
Rationale: (0.75×35 + 0.25×37).
17. Q: % yield of 50 g product from 60 g theoretical?
A: ~83.3%.
Rationale: (50÷60×100).
18. Q: What volume of H₂ at STP from 2 g Mg + excess HCl?
A: 0.0496 m³ / 49.6 dm³.
Rationale: Mg + 2HCl → H₂; 2 g Mg = 0.0825 mol H₂; 0.0825×24 = ~1.98 dm³
(approx).
19. Q: Empirical formula from 40% C, 6.7% H, 53.3% O?
A: CH₂O.
Rationale: Convert to moles, divide by smallest.
20. Q: Calculate concentration if 5 g NaOH in 500 cm³.
A: 0.25 mol dm⁻³.
Rationale: moles = 5/40=0.125; 0.125/0.5.
21. Q: Ionisation energy trend from Na to Mg?
A: Increases.
Rationale: More nuclear charge same shell.
22. Q: Why does atomic radius decrease across a period?
A: Increased nuclear charge pulls electrons closer.
23. Q: Why does Mg react faster with acid than Zn?
A: More reactive → lower ionisation energy.
24. Q: What is the lattice energy trend of MgO vs NaCl?
A: MgO > NaCl.
Rationale: Higher charges.
25. Q: Draw shape of NH₃.
A: Trigonal pyramidal.
Rationale: 3 bonds, 1 lone pair.
