10 free IB Physics B The Particulate Nature of Matter questions written in the style of IB Physics papers: 5 multiple-choice and 5 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers B.1 Thermal energy transfers, B.2 Greenhouse effect, B.3 Gas laws, B.4 Thermodynamics, B.5 Current & circuits. Work through the questions below, then generate a full B The Particulate Nature of Matter paper with a fresh set every time.
Generate a full B The Particulate Nature of Matter paper →The solar constant is 1360 W m−2 and the albedo of a planet is 0.25.
What is the mean intensity of solar radiation absorbed over the whole surface of the planet?
Answer: B
A mass of 0.05 kg of ice at 0 °C is added to 0.2 kg of water at 50 °C. Specific heat capacity of water = 4200 J kg−1 K−1; specific latent heat of fusion of ice = 3.34 × 105 J kg−1.
What is the final temperature?
Answer: A
A wall conducts thermal energy at rate P. The wall is replaced by one of the same material with 3 times the thickness and 2 times the area. The temperatures on each side stay the same. Which statements are correct?
I. The new rate of conduction is 2P/3.
II. The rate of conduction depends on the thermal conductivity of the material.
III. The new rate of conduction is 6P.
Answer: A
A cell of emf 12 V and internal resistance 2 Ω is connected to a 10 Ω resistor.
What is the potential difference across the terminals of the cell?
Answer: B
An ideal gas at pressure 2.0 × 105 Pa and temperature 290 K occupies a volume of 5 × 10−3 m3.
How many molecules are there in the gas?
Answer: C
0.20 kg of ice at −10 °C is added to 0.50 kg of water at 30 °C in an insulated container. cice = 2100 J kg−1 K−1, cwater = 4200 J kg−1 K−1, Lf = 3.34 × 105 J kg−1.
Calculate the energy needed to warm the ice to 0 °C.
Calculate the energy needed to melt all of the ice.
Calculate the energy released by the water cooling to 0 °C.
Deduce the final temperature and the mass of ice that remains.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 4200 J 0.20 × 2100 × 10 = 4200 J ✓ | 1 |
| (b) | 66 800 J 0.20 × 3.34 × 105 = 6.68 × 104 J ✓ | 1 |
| (c) | 63 000 J 0.50 × 4200 × 30 = 6.3 × 104 J ✓ | 1 |
| (d) | 0 °C; 0.024 kg 71 000 J needed > 63 000 J available ✓ so not all the ice melts and the final temperature is 0 °C ✓ ice melted = (63 000 − 4200)/3.34 × 105 = 0.176 kg ✓ ice remaining = 0.024 kg ✓ | 4 |
This question is about entropy and heat engines.
0.25 kg of water vaporizes at 373 K. Calculate the change in entropy of the water. (L = 2.26 × 106 J kg−1)
Explain, with reference to microstates, why this entropy change is positive.
A heat engine operates between 600 K and 300 K. It absorbs 3000 J per cycle and does 750 J of work. Compare its efficiency with the maximum possible efficiency.
A monatomic ideal gas at 2.0 × 105 Pa expands adiabatically from 1.0 × 10−3 m3 to 3 × 10−3 m3. Calculate the final pressure.
Explain why the temperature of the gas falls during this expansion.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 1510 J K−1 ΔS = Q/T = mL/T ✓ = 1510 J K−1 ✓ | 2 |
| (b) | gas has many more microstates molecules in the gas are more disordered ✓ there are many more microstates available so Ω and S = kBlnΩ increase ✓ | 2 |
| (c) | 25% vs 50% actual efficiency = 25% ✓ Carnot efficiency = 1 − Tc/Th = 50% ✓ actual is less, as expected for a real engine ✓ | 3 |
| (d) | 32000 Pa pV5/3 = constant ✓ p = 32000 Pa ✓ | 2 |
| (e) | work done by gas, Q = 0 no thermal energy is transferred (Q = 0) and the gas does work, so ΔU = −W ✓ internal energy decreases so temperature falls ✓ | 2 |
An electric kettle of power 2.2 kW heats 1.5 kg of water from 20 °C to 100 °C. Specific heat capacity of water = 4200 J kg−1 K−1.
Calculate the minimum time taken.
The kettle is left on for a further 60 s. Calculate the mass of water that boils away. (L = 2.26 × 106 J kg−1)
Explain, in molecular terms, why the temperature stays constant while the water boils.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 230 s Q = mcΔT = 504 000 J ✓ t = 229 s ✓ | 2 |
| (b) | 0.058 kg Q = 2200 × 60 = 132 000 J ✓ m = 0.058 kg ✓ | 2 |
| (c) | energy increases PE, not KE energy supplied increases the potential energy of molecules (breaking bonds) ✓ mean kinetic energy, and so temperature, stays constant ✓ | 2 |
A cell of emf 9.0 V and internal resistance 1.5 Ω is connected to a 6.0 Ω resistor and a 12 Ω resistor in parallel.
Calculate the total external resistance.
Calculate the current in the cell and the terminal potential difference.
Calculate the power dissipated in the 12 Ω resistor.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 4.0 Ω 4.0 Ω ✓ | 1 |
| (b) | 1.6 A; 6.5 V I = 9.0 ÷ 5.5 ✓ 1.64 A ✓ V = 6.5 V ✓ | 3 |
| (c) | 3.6 W V2/R = 6.52 ÷ 12 ✓ 3.6 W ✓ | 2 |
A cylinder with a movable piston contains 2 × 10−3 m3 of an ideal gas at a pressure of 1 × 105 Pa and a temperature of 300 K.
Calculate the number of moles of gas.
Calculate the mean kinetic energy of a molecule.
The gas is heated to 450 K at constant pressure. Calculate the new volume.
Calculate the work done by the gas during this expansion.
Explain, using the kinetic model, why the volume must increase if the pressure is to stay constant as the gas is heated.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 0.0802 mol n = pVRT ✓ 0.0802 mol ✓ | 2 |
| (b) | 6.21 × 10−21 J 32kBT = 6.21 × 10−21 J ✓ | 1 |
| (c) | 3.00 × 10−3 m3 VT constant ✓ 3.00 × 10−3 m3 ✓ | 2 |
| (d) | 100 J W = pΔV ✓ 100 J ✓ | 2 |
| (e) | faster molecules, fewer collisions per area the molecules move faster, so each collision transfers more momentum ✓ and they collide more often ✓ to keep the pressure constant the collision rate per unit area must fall, so the volume increases ✓ | 3 |
In the SL & HL syllabus, B The Particulate Nature of Matter covers B.1 Thermal energy transfers, B.2 Greenhouse effect, B.3 Gas laws, B.4 Thermodynamics, B.5 Current & circuits.
This page has 10 B The Particulate Nature of Matter questions with answers. For more, the free generator on mentorriyaz.in builds a new B The Particulate Nature of Matter paper with a full mark scheme each time you click.
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Meet Riyaz →Original IB-style practice questions written for mentorriyaz.in. These are not IB past paper questions, and this site is not affiliated with or endorsed by the International Baccalaureate Organization. Updated 2026-11-04. Paper generator · mentorriyaz.in