S1.2 The nuclear atom questions for IB Chemistry

83 questions on The nuclear atom, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.

IB Chemistry
Part of S1 Models of the particulate nature of matter
SL and HL

Questions by paper and level

SL and HL questions are for students at either level. HL only questions cover what only HL students study.

Paper	SL and HL	HL only	All
Paper 1A	35	7	42
Paper 1B	7	5	12
Paper 2	20	9	29
Every paper	62	21	83

Counted on 10 November 2026

Questions to try

Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.

Question 1 · CHEM-00068Paper 1A · 1 mark

What are the relative mass and the relative charge of a neutron?

A
Relative mass: 1; relative charge: +1
B
Relative mass: 1/1840; relative charge: −1
C
Relative mass: 1/1840; relative charge: 0
D
Relative mass: 1; relative charge: 0

The answer and whyCheck this one with a free account

Question 2 · CHEM-01201Paper 1B · 11 marks

Heavy water, D₂O, is used in some nuclear reactors. A student investigated how the density of mixtures of H₂O and D₂O depends on their composition, to find the D₂O content of a sample of reactor water.

Method:

Mixtures with known percentages of D₂O by volume were prepared using burettes.
10.00 cm³ of each mixture was transferred with a volumetric pipette (± 0.02 cm³) into a weighed beaker, and its mass was found on a balance (± 0.001 g).
All liquids were kept at 25.0 °C.

D₂O / % by volume	0	20	40	60	80	100
Mass of 10.00 cm³ / g ± 0.001 g	9.970	10.185	10.396	10.548	10.828	11.040

line of best fit

Mass of 10.00 cm³ of mixture (g) against percentage of D₂O by volume

(a)
Identify the independent variable and one controlled variable in this investigation.
1 mark
(b)
Calculate the density of pure D₂O, in g cm⁻³, to an appropriate number of significant figures.
1 mark
(c)
Calculate the percentage uncertainty in the density of pure D₂O.
2 marks
(d)
Identify the anomalous result and suggest one reason for it.
2 marks
(e)
Determine the gradient of the line of best fit, including its units.
2 marks
(f)
10.00 cm³ of the reactor water had a mass of 10.890 g. Determine its percentage of D₂O by volume.
1 mark
(g)
Explain why D₂O is denser than H₂O.
1 mark
(h)
Suggest why the temperature of all the liquids was kept the same.
1 mark

The markschemeCheck this one with a free account

Question 3 · CHEM-00505Paper 2 · 7 marks

The relative atomic mass of chlorine is 35.45. Chlorine exists as diatomic molecules, Cl₂.

(a)
Define the term relative atomic mass, A_r.
2 marks
(b)
Outline why A_r has no units.
1 mark
(c)
Calculate the mass, in g, of one chlorine molecule.
2 marks
(d)
Calculate the number of chlorine atoms in 2.50 dm³ of chlorine gas at STP. Use section 2 of the data booklet.
2 marks

The markschemeCheck this one with a free account

Question 4 · CHEM-00069Paper 1A · 1 mark

What are the numbers of protons, neutrons and electrons in the ion $_{27}^{59} C o^{3 +}$ ?

A
Protons: 27; neutrons: 32; electrons: 24
B
Protons: 27; neutrons: 32; electrons: 30
C
Protons: 27; neutrons: 59; electrons: 24
D
Protons: 32; neutrons: 27; electrons: 24

The answer and whyCheck this one with a free account

Question 5 · CHEM-01202Paper 1B · 12 marks

The rate at which a gas escapes (effuses) through a tiny hole depends on the mass of its molecules. A student filled a gas syringe with 50.0 cm³ of gas, attached a cap with a pinhole and placed a fixed mass on the plunger. The time for the volume to fall from 50.0 cm³ to 10.0 cm³ was measured with a hand-held stopwatch reading to 0.01 s. All measurements were made at 21 °C.

For gases at the same temperature, the time taken is proportional to $\sqrt{M}$ , where $M$ is the molar mass.

Gas	Molar mass / g mol⁻¹	Trial 1 / s	Trial 2 / s	Trial 3 / s
H₂	2.02	21.42	22.05	21.68
D₂	4.03	30.61	31.18	30.44
Y	?	26.37	26.85	26.52

(a)
Outline why ±0.01 s is not a realistic uncertainty for these times.
1 mark
(b)
Calculate the mean time for H₂ and its uncertainty, taking the uncertainty as half the range.
2 marks
(c)
Calculate the ratio of the mean time for D₂ to the mean time for H₂, and compare it with the ratio predicted from the molar masses.
2 marks
(d)
Determine the molar mass of gas Y.
2 marks
(e)
Y is a molecule of hydrogen. Deduce its formula, using isotopic masses of 1.01 for ¹H and 2.01 for ²H.
1 mark
(f)
Explain, in terms of particles, why D₂ takes longer than H₂ to escape through the hole.
2 marks
(g)
Suggest one source of systematic error in this method.
1 mark
(h)
Suggest one improvement that would reduce the random error in the timing.
1 mark

The markschemeCheck this one with a free account

Question 6 · CHEM-00815Paper 2 · 6 marks

The table shows information about three species.

Species	Protons	Neutrons	Electrons
$_{13}^{27} A l^{3 +}$
$_{15}^{31} P^{3 -}$
X	20	20	18

(a)
Complete the table for $_{13}^{27} A l^{3 +}$ and $_{15}^{31} P^{3 -}$ .
2 marks
(b)
Deduce the nuclear symbol, including the charge, of species X.
1 mark
(c)
Identify the two species in the table that are isoelectronic.
1 mark
(d)
State the relative mass and the relative charge of an electron.
2 marks

The markschemeCheck this one with a free account

Practice all 83 in Augment

Free with an account. Every question has its markscheme, and Augment keeps the ones you got wrong so you can come back to them.

Start free Log in

The notes on S1.2 The nuclear atom

Check your answers in Augment

A free account opens all 83 questions on The nuclear atom with their markschemes, and keeps a record of what you have marked.

Start free

Questions by paper and level

Questions to try

Practice all 83 in Augment

More questions in Models of the particulate nature of matter

Check your answers in Augment