Lesson 5.1.1

5.1.1 The mole, Avogadro constant and molar mass Quiz: Pearson Edexcel Chemistry, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.1.1, The mole, Avogadro constant and molar mass: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 5: Formulae, Equations and Amounts of Substance, written with Revision Ninja.

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The 20 questions

  1. What is the SI unit for amount of substance?

    • The litre, L
    • The gram, g
    • The kelvin, K
    • The mole, mol

  2. What is the value of the Avogadro constant?

    • 6.02 x 10^-23 mol-1
    • 6.02 x 10^23 mol-1
    • 6.02 x 10^23 g
    • 3.00 x 10^8 mol-1

  3. What are the units of molar mass?

    • mol g-1
    • g dm-3
    • mol dm-3
    • g mol-1

  4. How many moles are in 5.0 g of sodium hydroxide, NaOH? (Molar mass 40.0 g mol-1)

    • 0.200 mol
    • 0.0125 mol
    • 8.00 mol
    • 0.125 mol

  5. What is the mass of 0.50 mol of calcium carbonate, CaCO3? (Molar mass 100 g mol-1)

    • 100 g
    • 25 g
    • 200 g
    • 50 g

  6. How many molecules are in 0.25 mol of carbon dioxide?

    • 1.5 x 10^23
    • 2.4 x 10^24
    • 1.5 x 10^22
    • 6.0 x 10^23

  7. What is the molar mass of sulfuric acid, H2SO4? (H = 1, S = 32, O = 16)

    • 49 g mol-1
    • 96 g mol-1
    • 100 g mol-1
    • 98 g mol-1

  8. What is the molar mass of calcium hydroxide, Ca(OH)2? (Ca = 40, O = 16, H = 1)

    • 58 g mol-1
    • 56 g mol-1
    • 76 g mol-1
    • 74 g mol-1

  9. How many moles of sodium atoms are in 2.3 g of sodium? (Ar of Na = 23)

    • 0.050 mol
    • 0.23 mol
    • 1.0 mol
    • 0.10 mol

  10. How many atoms are in 0.1 mol of helium?

    • 6.0 x 10^23
    • 6.0 x 10^22
    • 1.2 x 10^23
    • 6.0 x 10^21

  11. What is the mass of 2.0 x 10^22 molecules of water? (Molar mass 18 g mol-1)

    • 1.1 g
    • 18 g
    • 0.60 g
    • 0.30 g

  12. What is the mass of 0.040 mol of iron? (Ar of Fe = 56)

    • 3.20 g
    • 1.40 g
    • 5.60 g
    • 2.24 g

  13. How many moles of oxygen atoms are in 0.5 mol of carbon dioxide?

    • 2.0 mol
    • 1.5 mol
    • 1.0 mol
    • 0.5 mol

  14. Which 10 g sample contains the greatest number of moles? (Molar masses: H2O 18, CO2 44, NaCl 58.5, Mg 24)

    • Sodium chloride, NaCl
    • Carbon dioxide, CO2
    • Water, H2O
    • Magnesium, Mg

  15. What is the mass of 0.75 mol of magnesium nitrate, Mg(NO3)2? (Mg = 24, N = 14, O = 16)

    • 111 g
    • 74 g
    • 37 g
    • 148 g

  16. How many ions are present in 0.2 mol of calcium chloride, CaCl2?

    • 1.2 x 10^23
    • 6.0 x 10^22
    • 2.4 x 10^23
    • 3.6 x 10^23

  17. Explain why 1 mol of H2 and 1 mol of O2 contain the same number of molecules but have different masses.

    • H2 contains more atoms than O2 does, so its molecules are heavier and its mass per mole is much larger
    • Both contain 6.02 x 10^23 molecules, but O2 has a larger molar mass (32 g mol-1) than H2 (2 g mol-1)
    • O2 contains fewer molecules than H2 does because it is a gas at room temperature and pressure
    • Both have the same mass because they contain the same number of molecules, so their masses must be equal

  18. How many molecules are in 4.0 g of methane, CH4? (Molar mass 16 g mol-1)

    • 9.0 x 10^22
    • 3.0 x 10^23
    • 6.0 x 10^22
    • 1.5 x 10^23

  19. Which expression correctly gives the number of moles of a substance?

    • n = mass x molar mass
    • n = molar mass / mass
    • n = mass / molar mass
    • n = mass x Avogadro constant

  20. What is the mass of 0.10 mol of sodium chloride? (Molar mass 58.5 g mol-1)

    • 0.585 g
    • 58.5 g
    • 11.7 g
    • 5.85 g

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