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Matter: hot or cold: OCR A‑Level Physics B questions

Every OCR A-Level Physics B exam question on 5.2.2 Matter: hot or cold, 2016–2025, with its mark scheme and examiner’s report.

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1,881 questions

  1. Q21

    June 2025 · Paper 1

    1 mark5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2025 Paper 1, question 21: The activation energy required to remove a water molecule from a body of water is 6.88 × 10–20 J. What temperature will produce a Boltzmann factor of 0.200 for

  2. Q35(a)

    June 2024 · Paper 1

    3 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2024 Paper 1, question 35(a): Calculate the energy required to break all the H-H bonds in one mole of hydrogen. energy = J [3]

  3. Q35(b)

    June 2024 · Paper 1

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2024 Paper 1, question 35(b): The average energy of hydrogen molecules at 300 K is below the energy needed to break the H-H bonds. Explain why hydrogen still reacts at a reasonable rate at 3

  4. Q1(a)(i)

    June 2023 · Paper 2

    1 mark5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2023 Paper 2, question 1(a)(i): Calculate the Boltzmann factor for this process. Human body temperature = 310 K Boltzmann factor = [1]

  5. Q1(a)(ii)

    June 2023 · Paper 2

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2023 Paper 2, question 1(a)(ii): Explain how an individual particle can gain sufficient energy to complete a reaction when the energy required is far greater than the average energy of the part

  6. Q1(b)(i)

    June 2023 · Paper 2

    3 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2023 Paper 2, question 1(b)(i): Explain why this change to the Boltzmann factor affects the rate at which the digestion reaction takes place. Include a description of the information the Boltz

  7. Q1(b)(ii)

    June 2023 · Paper 2

    3 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2023 Paper 2, question 1(b)(ii): The enzyme increases the Boltzmann factor at 310 K to a value of 6.7 × 10–7 by reducing the activation energy required for the reaction. Calculate the activatio

  8. Q16

    June 2022 · Paper 1

    1 mark5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2022 Paper 1, question 16: The activation energy required to remove an electron from a filament is 9.00 × 10–20 J. What temperature will produce a Boltzmann factor of 0.0100 for this proc

  9. Q9

    June 2022 · Paper 2

    6 marks6.1.2 Charge and field5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2022 Paper 2, question 9: 9* This question is about the slow rate of fusion in the Sun (lines 33 – 47). The temperature of the core of the Sun is 1.5 × 107 K. Assuming that two protons n

  10. Q35(a)

    November 2021 · Paper 1

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2021 Paper 1, question 35(a): Use the graph to estimate the temperature T when E = kT for this process. temperature T = K [2]

  11. Q35(b)

    November 2021 · Paper 1

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2021 Paper 1, question 35(b): Explain why the process completes at this temperature, but may occur at a significant rate at temperatures as low as T 20. [2]

  12. Q40(a)(i)

    November 2020 · Paper 1

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2020 Paper 1, question 40(a)(i): Show that the energy per hydrogen bond is about 7 × 10−20 J. [2] To set the custard, the hydrogen bonds have to be broken by baking it in an oven at 70°C.

  13. Q40(a)(ii)

    November 2020 · Paper 1

    1 mark5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2020 Paper 1, question 40(a)(ii): Calculate the typical thermal energy of molecules at 70°C (343 K). thermal energy = J [1]

  14. Q40(a)(iii)

    November 2020 · Paper 1

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2020 Paper 1, question 40(a)(iii): Breaking hydrogen bonds alters the protein molecules and thickens the custard. Calculate the fraction of water molecules at 70°C that have sufficient thermal en

  15. Q40(a)(iv)

    November 2020 · Paper 1

    2 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2020 Paper 1, question 40(a)(iv): Only a low fraction of molecules has enough energy to break hydrogen bonds. Explain how the cooking reaction can still proceed at a reasonable rate at 70°C. [2]

  16. Q40(b)

    November 2020 · Paper 1

    1 mark5.2.2 Matter: hot or cold
    The whole paper ↗
    November 2020 Paper 1, question 40(b): To lightly burn the sugar on top of the custard, much stronger covalent bonds must be broken. The graph shows how the Boltzmann factor changes with temperature

  17. Q30

    June 2019 · Paper 1

    1 mark5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2019 Paper 1, question 30: The graph shows how the Boltzmann factor f = e−E /kT varies with absolute temperature T for an excitation process involving activation energy E. 1 f =e –E/kT 0.

  18. Q9

    June 2019 · Paper 2

    4 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2019 Paper 2, question 9: An estimate of the atmospheric pressure p at height h above the surface of Mars can be found from the equation ln p = ln ps – mgh kT where ps is the pressure at

  19. Q39(b)(ii)

    June 2018 · Paper 1

    4 marks5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2018 Paper 1, question 39(b)(ii): The escape velocity for planet Earth is 11.2 km s−1. Use the Boltzmann factor to estimate the number of H2 molecules per mole with sufficient energy to escape t

  20. Q6(c)

    June 2018 · Paper 2

    6 marks3.1.2 Sensing5.2.2 Matter: hot or cold
    The whole paper ↗
    June 2018 Paper 2, question 6(c): This question is about conduction in metals and in semiconductors. (c)* The conductivity σ of semiconductors such as ntc thermistors increases dramatically with
All 25 questions on Matter: hot or cold, as a list
  1. June 2025, Paper 1, Q21 (1 mark): The activation energy required to remove a water molecule from a body of water is 6.88 × 10–20 J. What temperature will produce a Boltzmann factor of 0.200 for
  2. June 2024, Paper 1, Q35(a) (3 marks): Calculate the energy required to break all the H-H bonds in one mole of hydrogen. energy = J [3]
  3. June 2024, Paper 1, Q35(b) (2 marks): The average energy of hydrogen molecules at 300 K is below the energy needed to break the H-H bonds. Explain why hydrogen still reacts at a reasonable rate at 3
  4. June 2023, Paper 2, Q1(a)(i) (1 mark): Calculate the Boltzmann factor for this process. Human body temperature = 310 K Boltzmann factor = [1]
  5. June 2023, Paper 2, Q1(a)(ii) (2 marks): Explain how an individual particle can gain sufficient energy to complete a reaction when the energy required is far greater than the average energy of the part
  6. June 2023, Paper 2, Q1(b)(i) (3 marks): Explain why this change to the Boltzmann factor affects the rate at which the digestion reaction takes place. Include a description of the information the Boltz
  7. June 2023, Paper 2, Q1(b)(ii) (3 marks): The enzyme increases the Boltzmann factor at 310 K to a value of 6.7 × 10–7 by reducing the activation energy required for the reaction. Calculate the activatio
  8. June 2022, Paper 1, Q16 (1 mark): The activation energy required to remove an electron from a filament is 9.00 × 10–20 J. What temperature will produce a Boltzmann factor of 0.0100 for this proc
  9. June 2022, Paper 2, Q9 (6 marks): 9* This question is about the slow rate of fusion in the Sun (lines 33 – 47). The temperature of the core of the Sun is 1.5 × 107 K. Assuming that two protons n
  10. November 2021, Paper 1, Q35(a) (2 marks): Use the graph to estimate the temperature T when E = kT for this process. temperature T = K [2]
  11. November 2021, Paper 1, Q35(b) (2 marks): Explain why the process completes at this temperature, but may occur at a significant rate at temperatures as low as T 20. [2]
  12. November 2020, Paper 1, Q40(a)(i) (2 marks): Show that the energy per hydrogen bond is about 7 × 10−20 J. [2] To set the custard, the hydrogen bonds have to be broken by baking it in an oven at 70°C.
  13. November 2020, Paper 1, Q40(a)(ii) (1 mark): Calculate the typical thermal energy of molecules at 70°C (343 K). thermal energy = J [1]
  14. November 2020, Paper 1, Q40(a)(iii) (2 marks): Breaking hydrogen bonds alters the protein molecules and thickens the custard. Calculate the fraction of water molecules at 70°C that have sufficient thermal en
  15. November 2020, Paper 1, Q40(a)(iv) (2 marks): Only a low fraction of molecules has enough energy to break hydrogen bonds. Explain how the cooking reaction can still proceed at a reasonable rate at 70°C. [2]
  16. November 2020, Paper 1, Q40(b) (1 mark): To lightly burn the sugar on top of the custard, much stronger covalent bonds must be broken. The graph shows how the Boltzmann factor changes with temperature
  17. June 2019, Paper 1, Q30 (1 mark): The graph shows how the Boltzmann factor f = e−E /kT varies with absolute temperature T for an excitation process involving activation energy E. 1 f =e –E/kT 0.
  18. June 2019, Paper 2, Q9 (4 marks): An estimate of the atmospheric pressure p at height h above the surface of Mars can be found from the equation ln p = ln ps – mgh kT where ps is the pressure at
  19. June 2018, Paper 1, Q39(b)(ii) (4 marks): The escape velocity for planet Earth is 11.2 km s−1. Use the Boltzmann factor to estimate the number of H2 molecules per mole with sufficient energy to escape t
  20. June 2018, Paper 2, Q6(c) (6 marks): This question is about conduction in metals and in semiconductors. (c)* The conductivity σ of semiconductors such as ntc thermistors increases dramatically with
  21. June 2017, Paper 1, Q20 (1 mark): At 300 K a process has an activation energy E 10 kT . = The temperature is raised to 330 K. Which statement about the rate of the process is correct? It will in
  22. June 2017, Paper 2, Q5(a) (3 marks): Explain how the graphs in Fig. 5.1 show that line C represents the process with the greatest activation energy E. [3]
  23. June 2017, Paper 2, Q5(b)(i) (3 marks): The Boltzmann factor for water molecules escaping the liquid and entering the vapour state is 4.9 × 10–8 at 310 K. Calculate the activation energy required for
  24. June 2017, Paper 2, Q5(b)(ii) (2 marks): Explain how particles with an average energy lower than the activation energy gain enough energy to escape into the vapour. [2]
  25. June 2017, Paper 2, Q5(b)(iii) (6 marks): This question is about the Boltzmann factor, f = e–E/kT. 5 Fig. 5.1 shows how the Boltzmann factor varies with temperature for three processes: A, B and C. 1 Bo

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