IB Diploma Physics chapter 2: The particulate nature of matter MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
53 exam-style questions on The particulate nature of matter, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Ten The particulate nature of matter questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. The solar constant is 1360 W m−2 and the Earth's mean albedo is 0.30. What is the mean solar power absorbed per square metre of the Earth's surface?
A
340 W m−2
B
240 W m−2
C
950 W m−2
D
100 W m−2
Show answer
Answer: B. Average incident intensity = 1360 ÷ 4 = 340 W m−2; 70% is absorbed: 0.70 × 340 = 238 ≈ 240 W m−2. 950 W m−2 forgets the factor of 4; 100 W m−2 is the reflected part.
2. A battery's terminal p.d. is 12.0 V when no current flows and 11.0 V when it supplies 2.0 A. What is its internal resistance?
A
5.5 Ω
B
0.50 Ω
C
6.0 Ω
D
2.0 Ω
Show answer
Answer: B. The open-circuit p.d. equals the emf, 12.0 V. The 'lost volts' = 12.0 − 11.0 = 1.0 V = Ir, so r = 1.0 ÷ 2.0 = 0.50 Ω. 5.5 Ω is the external resistance.
3. The temperature of a gas rises from 27 °C to 327 °C. By what factor does the mean kinetic energy of its molecules increase?
A
12
B
4
C
√2
D
2
Show answer
Answer: D. Mean kinetic energy is proportional to absolute temperature: 300 K to 600 K doubles it. Using Celsius (327 ÷ 27 ≈ 12) is the classic trap.
4. Which method of thermal energy transfer cannot take place in a solid?
A
conduction
B
absorption of thermal radiation
C
convection
D
emission of thermal radiation
Show answer
Answer: C. Convection needs the bulk movement of a fluid, with warmer, less dense regions rising. Particles in a solid cannot flow, so only conduction and radiation occur.
5. Arctic sea ice melts and is replaced by dark open ocean. What is the effect on the absorption of solar radiation in that region?
A
the albedo increases, so more solar radiation is absorbed
B
the emissivity of the surface falls to zero, so no radiation is emitted
C
the albedo decreases, so less solar radiation is absorbed
D
the albedo decreases, so more solar radiation is absorbed and warming increases
Show answer
Answer: D. Ice reflects much more light than dark water. A lower albedo means a larger fraction is absorbed, which causes more melting: a positive feedback.
6. A glass window has area 2.0 m² and thickness 4.0 mm. Its surfaces are at 15 °C and 5 °C. Thermal conductivity of glass = 0.80 W m−1 K−1. What is the rate of energy transfer by conduction?
A
2.0 × 103 W
B
6.4 × 10−2 W
C
4.0 × 103 W
D
4.0 W
Show answer
Answer: C. ΔQ/Δt = kAΔT/Δx = 0.80 × 2.0 × 10 ÷ 0.0040 = 4000 W. 4.0 W comes from leaving the thickness in millimetres.
7. Why is the density of steam much lower than the density of liquid water?
A
each molecule in steam has less mass
B
the molecules in steam are much further apart on average
C
the molecules in steam move more slowly
D
the molecules in steam are smaller
Show answer
Answer: B. The molecules are identical in both phases; in the gas they are roughly ten times further apart, so the same mass occupies far more volume.
8. A light-dependent resistor (LDR) is used in a potential divider. What happens to the resistance of the LDR as the light falling on it becomes brighter?
A
it stays the same
B
it increases then decreases
C
it decreases
D
it increases
Show answer
Answer: C. More light frees more charge carriers in the LDR's semiconductor, so its resistance falls: from about a megohm in darkness to hundreds of ohms in bright light.
9. Which of these atmospheric gases is not a significant greenhouse gas?
A
methane, CH4
B
nitrous oxide, N2O
C
water vapour, H2O
D
nitrogen, N2
Show answer
Answer: D. Nitrogen makes up most of the atmosphere, but its symmetric two-atom molecule does not absorb infrared. CH4, H2O and N2O all do.
10. What is the internal energy of a substance?
A
the thermal energy transferred to it by heating
B
its temperature multiplied by its mass
C
the total kinetic energy of its particles only
D
the total random kinetic energy and intermolecular potential energy of its particles
Show answer
Answer: D. Internal energy includes both random kinetic energy and the potential energy from intermolecular forces. Thermal energy (heat) is energy in transit, not energy stored.
The particulate nature of matter: questions students ask
How many The particulate nature of matter MCQs are there?
53, each with the answer and a short explanation, across 4 topics: B.1 Thermal energy transfers, B.2 Greenhouse effect, B.3 Gas laws, B.5 Current and circuits. Every chapter test draws ten of them, so you can take it many times.
Is the IB Diploma Physics chapter 2 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
