Lesson 5.3.2.3

5.3.2.3 Using moles to balance equations (HT only) Quiz: AQA Combined Science, Unit 10

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.3.2.3, Using moles to balance equations (HT only): 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 10: Quantitative chemistry, written with Revision Ninja.

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The 20 questions

  1. What is the first calculation step when finding balancing numbers from masses?

    • Multiply by Mr
    • Add atomic numbers
    • Convert to moles
    • Divide by volume

  2. After converting masses to moles, what is the next step to find balancing numbers?

    • Add together
    • Divide by smallest
    • Multiply by largest
    • Multiply by mass

  3. 0.2 mol of Mg reacts with 0.1 mol of O2 to form MgO. What are the balancing numbers for Mg : O2 : MgO?

    • 1 : 2 : 2
    • 1 : 1 : 1
    • 2 : 1 : 2
    • 3 : 1 : 3

  4. 0.4 mol of Al reacts with 0.3 mol of O2 to form Al2O3. What are the balancing numbers for Al : O2 : Al2O3?

    • 1 : 1 : 1
    • 4 : 3 : 4
    • 2 : 3 : 2
    • 4 : 3 : 2

  5. 0.05 mol of hydrogen reacts with 0.025 mol of oxygen to form water. What are the balancing numbers for H2 : O2 : H2O?

    • 1 : 1 : 1
    • 1 : 2 : 2
    • 2 : 1 : 1
    • 2 : 1 : 2

  6. 0.1 mol of carbon reacts with 0.1 mol of oxygen molecules to form CO2. What are the balancing numbers for C : O2 : CO2?

    • 2 : 1 : 2
    • 1 : 1 : 2
    • 1 : 2 : 1
    • 1 : 1 : 1

  7. 0.1 mol of hydrogen gas reacts with 0.1 mol of chlorine gas to form hydrogen chloride. What are the balancing numbers for H2 : Cl2 : HCl?

    • 1 : 2 : 2
    • 1 : 1 : 2
    • 1 : 1 : 1
    • 2 : 1 : 2

  8. 0.1 mol of calcium reacts with 0.2 mol of hydrochloric acid, giving 0.1 mol of CaCl2 and 0.1 mol of H2. Which equation is balanced?

    • Ca + 2HCl -> CaCl2 + H2
    • 2Ca + HCl -> 2CaCl + H2
    • Ca + 2HCl -> CaCl + H2
    • Ca + HCl -> CaCl + H2

  9. 0.2 mol of aluminium reacts with 0.3 mol of chlorine gas to form AlCl3. What are the balancing numbers for Al : Cl2 : AlCl3?

    • 2 : 3 : 3
    • 2 : 3 : 2
    • 3 : 2 : 2
    • 1 : 1 : 1

  10. 2.0 g of hydrogen reacts with 16 g of oxygen to form water. What are the balancing numbers for H2 : O2 : H2O?

    • 2 : 1 : 2
    • 1 : 2 : 2
    • 1 : 1 : 1
    • 2 : 2 : 1

  11. Which value is NOT needed to calculate balancing numbers from masses?

    • Avogadro constant
    • Relative formula mass
    • Mass in grams
    • Balanced equation

  12. 2.0 g of calcium (0.05 mol) reacts with 0.8 g of oxygen (0.025 mol). Which equation is balanced?

    • Ca + O2 -> CaO
    • 2Ca + O2 -> 2CaO
    • 2Ca + 2O2 -> 2CaO
    • Ca + 2O2 -> CaO2

  13. The mole ratio of N2 : H2 : NH3 in a reaction is 1 : 3 : 2. Which balanced equation matches?

    • N2 + 2H2 -> 2NH3
    • N2 + H2 -> NH3
    • 2N2 + 3H2 -> NH3
    • N2 + 3H2 -> 2NH3

  14. The mole ratio of Mg : HCl : MgCl2 : H2 in a reaction is 1 : 2 : 1 : 1. Which balanced equation matches?

    • Mg + 2HCl -> MgCl + H2
    • Mg + HCl -> MgCl2 + H2
    • 2Mg + HCl -> 2MgCl + H2
    • Mg + 2HCl -> MgCl2 + H2

  15. The mole ratio of CH4 : O2 : CO2 : H2O in a reaction is 1 : 2 : 1 : 2. Which balanced equation matches?

    • CH4 + 2O2 -> CO2 + 2H2O
    • CH4 + 3O2 -> CO2 + 2H2O
    • CH4 + O2 -> CO2 + 2H2O
    • CH4 + O2 -> CO2 + H2O

  16. In the reaction 2H2 + O2 -> 2H2O, 0.2 mol of H2 reacts with 0.1 mol of O2. How many moles of H2O form?

    • 0.4 mol
    • 0.05 mol
    • 0.1 mol
    • 0.2 mol

  17. Why are moles used instead of masses to find equation balancing numbers?

    • They are heavier
    • Constant volume
    • Easier to measure
    • Relate to particles

  18. 0.3 mol of Na2O reacts with 0.3 mol of H2O. Which balanced equation matches the mole ratio Na2O : H2O : NaOH of 1 : 1 : 2?

    • Na2O + H2O -> NaOH
    • 2Na2O + H2O -> NaOH
    • Na2O + 2H2O -> NaOH
    • Na2O + H2O -> 2NaOH

  19. 0.1 mol of sodium reacts with 0.05 mol of chlorine gas. Which balanced equation is correct?

    • 2Na + 2Cl2 -> 2NaCl
    • 2Na + Cl2 -> 2NaCl
    • Na + Cl2 -> NaCl
    • Na + 2Cl2 -> NaCl2

  20. 6.5 g of zinc (0.1 mol) reacts with 7.3 g of hydrochloric acid (0.2 mol) to form zinc chloride and hydrogen. Which balanced equation matches?

    • Zn + 2HCl -> ZnCl2 + H2
    • 2Zn + HCl -> 2ZnCl + H2
    • Zn + 2HCl -> ZnCl + H2
    • Zn + HCl -> ZnCl + H2

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