Lesson 4.3.2.3

4.3.2.3 Using moles to balance equations (HT only) Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.3.2.3, Using moles to balance equations (HT only): 20 multiple choice questions for the AQA GCSE Chemistry (8462), Unit 3: Quantitative chemistry, written with Revision Ninja.

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The 20 questions

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

    • Multiply by Avogadro
    • Convert mass to moles
    • Add relative masses
    • Divide by volume

  2. What whole-number ratio of moles of Mg to O2 is given by 0.1 mol and 0.05 mol?

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

  3. A reaction has 0.2 mol A and 0.6 mol B. What is the simplest ratio of A to B?

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

  4. A reaction uses 4 g of H2 (2 mol) and 32 g of O2 (1 mol). What balancing numbers are needed for H2 and O2?

    • 2 H2 and 1 O2
    • 1 H2 and 1 O2
    • 1 H2 and 2 O2
    • 4 H2 and 1 O2

  5. 0.2 mol Al reacts with 0.3 mol Cl2 to form AlCl3. Which balanced equation fits?

    • Al + Cl2 -> AlCl3
    • 2Al + Cl2 -> 2AlCl3
    • Al + 3Cl2 -> AlCl3
    • 2Al + 3Cl2 -> 2AlCl3

  6. How do you simplify a set of whole-number mole values to find a ratio?

    • Square root each
    • Add them together
    • Divide by smallest
    • Multiply by largest

  7. A reaction uses 0.4 mol X and 0.1 mol Y. What is the simplest ratio of X to Y?

    • 5 : 1
    • 4 : 1
    • 1 : 4
    • 2 : 1

  8. 0.25 mol of carbon reacts with 0.5 mol of oxygen molecules. What is the simplest ratio of C to O2?

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

  9. 2.4 g of Mg (Mr 24) reacts with 1.6 g of O2 (Mr 32) to form MgO. Which balanced equation fits?

    • 2Mg + 2O2 -> MgO
    • Mg + O2 -> MgO
    • 2Mg + O2 -> 2MgO
    • Mg + 2O2 -> MgO

  10. 0.4 mol Na reacts with 0.2 mol Cl2 to form NaCl. Which equation fits?

    • 2Na + 2Cl2 -> NaCl
    • 4Na + Cl2 -> 2NaCl
    • 2Na + Cl2 -> 2NaCl
    • Na + Cl2 -> NaCl

  11. 0.3 mol of H2 reacts with 0.15 mol of O2. What coefficient for O2 is needed in 2H2 + ?O2 -> 2H2O?

    • 2
    • 1
    • 0.5
    • 3

  12. 0.5 mol Fe reacts with 0.375 mol O2 to form Fe2O3. Which balanced equation fits?

    • 2Fe + 3O2 -> Fe2O3
    • Fe + O2 -> Fe2O3
    • 4Fe + 3O2 -> Fe2O3
    • 4Fe + 3O2 -> 2Fe2O3

  13. 0.2 mol Ca reacts with 0.2 mol Cl2 to form CaCl2. Which balanced equation fits?

    • Ca + Cl2 -> 2CaCl2
    • 2Ca + Cl2 -> CaCl2
    • Ca + 2Cl2 -> CaCl2
    • Ca + Cl2 -> CaCl2

  14. Why must masses be converted to moles before comparing in reactions?

    • Masses always add up
    • Atoms are destroyed
    • Volume changes constantly
    • Different Mr values

  15. 0.9 mol of A reacts with 0.3 mol of B. What is the simplest ratio of A to B?

    • 2 : 1
    • 9 : 3
    • 1 : 3
    • 3 : 1

  16. A reaction gives 0.1 mol X reacting with 0.3 mol Y to form XY3. Which balanced equation fits?

    • 2X + Y -> X2Y
    • X + 2Y -> XY3
    • X + Y -> XY
    • X + 3Y -> XY3

  17. 0.5 mol H2 reacts with 0.25 mol O2 to form water. What coefficient for H2 is needed in ?H2 + O2 -> ?H2O?

    • 4
    • 0.5
    • 2
    • 1

  18. A reaction gives 2.0 mol product from 1.0 mol of A and 2.0 mol of B. Which balanced equation fits?

    • A + 2B -> 2C
    • A + 2B -> C
    • 2A + B -> C
    • A + B -> C

  19. 0.6 mol of carbon reacts with 0.3 mol of O2 to form carbon monoxide. Which balanced equation fits?

    • 2C + O2 -> CO2
    • C + O2 -> CO
    • C + 2O2 -> CO2
    • 2C + O2 -> 2CO

  20. 0.8 mol of N2 reacts with 2.4 mol of H2 to form ammonia. Which balanced equation fits?

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

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