IB Diploma Chemistry chapter 1: Structure 1: Models of the particulate nature of matter MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

45 exam-style questions on Structure 1: Models of 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.

45 questions · 5 topics · 10 per test

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What chapter 1 covers

Ten Structure 1: Models of 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. Which technique is best for separating ethanol (boiling point 78 °C) from water (boiling point 100 °C)?

  1. A
    paper chromatography
  2. B
    filtration
  3. C
    crystallization
  4. D
    fractional distillation
Show answer

Answer: D. Ethanol and water are miscible liquids with different boiling points, so fractional distillation separates them; ethanol distils off first. Filtration only removes an insoluble solid from a liquid.

2. At the same temperature and pressure, which gas sample contains the same number of molecules as 2.0 dm3 of oxygen, O2?

  1. A
    1.3 dm3 of ozone, O3, because each molecule has more atoms
  2. B
    4.0 dm3 of helium, because helium is monatomic
  3. C
    2.0 g of hydrogen gas
  4. D
    2.0 dm3 of carbon dioxide
Show answer

Answer: D. Avogadro's law: equal volumes of gases at the same temperature and pressure contain equal numbers of molecules, whatever the gas.

3. What mass of sodium hydroxide (M = 40.00 g mol−1) is needed to make 250 cm3 of a 0.200 mol dm−3 solution?

  1. A
    8.00 g
  2. B
    2.00 g
  3. C
    0.0500 g
  4. D
    2000 g
Show answer

Answer: B. n = c × V = 0.200 × 0.250 = 0.0500 mol; m = 0.0500 × 40.00 = 2.00 g. Using 250 without converting cm3 to dm3 gives 2000 g.

4. What is the molar mass of calcium nitrate, Ca(NO3)2? (Ar: Ca 40.08, N 14.01, O 16.00)

  1. A
    102.09 g mol−1
  2. B
    116.10 g mol−1
  3. C
    164.10 g mol−1
  4. D
    132.10 g mol−1
Show answer

Answer: C. M = 40.08 + 2 × (14.01 + 3 × 16.00) = 40.08 + 2 × 62.01 = 164.10 g mol−1. The bracket multiplies every atom inside it, including all six oxygens.

5. What is the condensed electron configuration of an iron atom (Z = 26)?

  1. A
    [Ar] 3d8
  2. B
    [Ar] 3d6 4s2
  3. C
    [Ar] 3d7 4s1
  4. D
    [Ar] 4s2 4p6
Show answer

Answer: B. After argon (18 electrons), 4s fills before 3d: 4s2 then 3d6 makes 26. Iron is not one of the Cr/Cu exceptions.

6. Boron has two isotopes, boron-10 and boron-11, and a relative atomic mass of 10.8. What is the percentage abundance of boron-10?

  1. A
    80%
  2. B
    50%
  3. C
    20%
  4. D
    10.8%
Show answer

Answer: C. 10x + 11(100 − x) = 1080, so 1100 − x = 1080 and x = 20%. The answer 80% is the abundance of boron-11; Ar is closer to 11, so boron-11 must be the major isotope.

7. A fixed mass of gas occupies 300 cm3 at 27 °C. It is heated to 127 °C at constant pressure. What is its new volume?

  1. A
    400 cm3
  2. B
    1410 cm3
  3. C
    225 cm3
  4. D
    300 cm3
Show answer

Answer: A. V ∝ T in kelvin: V = 300 × 400 ÷ 300 = 400 cm3. Using Celsius (300 × 127 ÷ 27) gives about 1410 cm3.

8. What is the mass of 0.250 mol of sodium carbonate, Na2CO3 (M = 105.99 g mol−1)?

  1. A
    26.5 g
  2. B
    424 g
  3. C
    2.36 × 10−3 g
  4. D
    53.0 g
Show answer

Answer: A. m = n × M = 0.250 × 105.99 = 26.5 g. Dividing M by n (424 g) is the common slip.

9. How does a line emission spectrum differ from a continuous spectrum?

  1. A
    it shows only certain frequencies, as bright lines on a dark background
  2. B
    it contains every wavelength of visible light
  3. C
    it is produced when electrons move up to higher energy levels
  4. D
    it is produced only by hot solids
Show answer

Answer: A. Excited gaseous atoms emit only the frequencies matching the gaps between their energy levels, so we see separate lines. Moving up a level absorbs energy rather than emitting it.

10. Which pair of atoms contain the same number of neutrons?

  1. A
    12C and 14N
  2. B
    14C and 16O
  3. C
    14C and 14N
  4. D
    16O and 18O
Show answer

Answer: B. Carbon-14 has 14 − 6 = 8 neutrons and oxygen-16 has 16 − 8 = 8. Equal mass numbers (14C and 14N) do not mean equal neutrons: 8 and 7.

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Structure 1: Models of the particulate nature of matter: questions students ask

How many Structure 1: Models of the particulate nature of matter MCQs are there?

45, each with the answer and a short explanation, across 5 topics: S1.1 Introduction to the particulate nature of matter, S1.2 The nuclear atom, S1.3 Electron configurations, S1.4 Counting particles by mass: the mole, S1.5 Ideal gases. Every chapter test draws ten of them, so you can take it many times.

Is the IB Diploma Chemistry chapter 1 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.

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