IB
Chemistry (New Syllabus)
Question Bank
Free International Baccalaureate Diploma Programme Exam Style Questions
Sharpen your skills in the new syllabus (2025) for International Baccalaureate Chemistry with our curated IB past paper questions. Covering fundamental to advanced concepts, these questions will assist in consolidating your knowledge and acing the IB Chemistry (2025) syllabus in the first examinations in 2025.
Question 1
What is the total number of carbon atoms in three mole of CH3CH2COOH?
[ 1 ]
A.
$9$
B.
$6.02 \times 10^{23} $
C.
$1.80 \times 10^{24} $
D.
$5.42 \times 10^{24} $
Rationale
$3 \space \text{mole} \times 3 \space \text{atoms of C} \times 6.02 \times 10^{23} = 5.42 \times 10^{24} $
Question 2
What are the major sources of error in heat combustion reaction experiments?
I. Not all heat energy heated the water.
II. Incomplete combustion reaction.
III. The thermometer only measured the bottom of the beaker.
[ 1 ]
[© Abaccus Ltd 2022]
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II, and III
Question 3
Which equation represents sublimation?
[ 1 ]
A.
$\mathrm { CaCO } _ { 3 } ( \mathrm {s} ) + 2 \mathrm { HCl } ( \mathrm { aq } ) \rightarrow \mathrm { CaCl } _ { 2 } ( \mathrm { aq } ) + \mathrm { CO } _ { 2 } ( \mathrm {g} ) + \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } )$
B.
$\mathrm { I } _ { 2 } ( \mathrm {s} ) \rightarrow \mathrm { I } _ { 2 } ( \mathrm {g} )$
C.
$2 \mathrm { Al } ( \mathrm { s } ) + 3 \mathrm { I } _ { 2 } ( \mathrm {g} ) \rightarrow 2 \mathrm { All } _ { 3 } ( \mathrm {s} )$
D.
$\mathrm { HgCl } _ { 2 } ( \mathrm {g} ) \rightarrow \mathrm { HgCl } _ { 2 } ( \mathrm {s} )$
Rationale
Solid to gas transitions are called sublimation reactions
Question 4
What is the amount, in moles, of sulfate ions in 100 cm3 of 0.050 mol dm-3 FeSO4(aq)?
[ 1 ]
A.
0.005
B.
0.050
C.
0.500
D.
5.00
Rationale
n = CV = 0.1 x 0.05 = 0.005
Question 5
Which statement is correct for the ion $_4^9{\text{B}}{{\text{e}}^{2 + }}$?
[ 1 ]
A.
The ion contains 13 subatomic particles in the nucleus.
B.
The ion contains more protons than neutrons in the nucleus.
C.
The ion has an electron configuration of 1s22s2.
D.
Most of the total volume of the ion is empty space.
Rationale
It contains 9 subatomic particles in the nucleus
It contains more neutrons than protons
It has a configuration of 1s2 only
D is correct (for all ions/atoms)
Question 6
Successive ionization energies for an element, X, are shown in the table below.
| Electrons removed | 1st | 2nd | 3rd | 4th | 5th |
|---|---|---|---|---|---|
| Ionization energy / kJ mol-1 | 590 | 1145 | 4912 | 6491 | 8153 |
[ 1 ]
What is the most likely formula for the ion of X?
A.
X+
B.
X2+
C.
X3+
D.
X4+
Rationale
The biggest jump is between the second and third ionization energies, indicating a change in energy levels. This indicates that there are two valence electrons, which will create a 2+ ion.
Question 7
The diagram shows the first ionization energies of four consecutive elements in the periodic table. Which element is in group 15?
[ 1 ]
[© Abaccus Ltd 2022]
A.
A
B.
B
C.
C
D.
D
Rationale
After group 15, the next electron in the group 16 element is paired up in one of the three p shells. In group 15, each is half filled, which is more stable. Thus, removing an electron from a group 16 element requires less energy, meaning D is group 16 and C is group 15.
Question 8
The graph represents the first ten ionization energies (IE) of an X. What is element X?
[ 1 ]
[© Abaccus Ltd 2022]
A.
F
B.
P
C.
S
D.
Cl
Rationale
The element must have a minimum of 11 electrons, so it cannot be F. It also must have 7 valence electrons due to energy jump in IE between the 7th and 8th IE. Thus, the element must be Cl.
Question NaN
What is the total number of carbon atoms in three mole of CH3CH2COOH?
[ 1 ]
A.
$9$
B.
$6.02 \times 10^{23} $
C.
$1.80 \times 10^{24} $
D.
$5.42 \times 10^{24} $
Rationale
$3 \space \text{mole} \times 3 \space \text{atoms of C} \times 6.02 \times 10^{23} = 5.42 \times 10^{24} $
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