Solved Past Papers + Notes (Relevant to Recent Syllabus)

* 0000800000001 * DFD



,










,




Cambridge IGCSE™

¬OŠ. 4mHuOªEŠ_{5€W
¬„ey\ª{yM t‘VŠ†|o‚
¥EEUuUeuE5e Ue55U
* 1 6 0 3 3 7 3 6 0 7 *




CHEMISTRY 0620/43
Paper 4 Theory (Extended) October/November 2025

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● You may use a calculator.
● You should show all your working and use appropriate units.


INFORMATION
● The total mark for this paper is 80.
● The number of marks for each question or part question is shown in brackets [ ].
● The Periodic Table is printed in the question paper.




This document has 16 pages. Any blank pages are indicated.


DC (PB/CB) 347599/3
© UCLES 2025 [Turn over

, * 0000800000002 * DFD




DO NOT WRITE IN THIS MARGIN
2
,










,

1 Atoms and ions are made from particles called electrons, neutrons and protons.

(a) Complete Table 1.1.

Table 1.1

particle relative charge relative mass
1
electron –1
1840




DO NOT WRITE IN THIS MARGIN
neutron


proton

[2]

(b) Table 1.2 shows information about some atoms or ions.

Complete Table 1.2.

Table 1.2




DO NOT WRITE IN THIS MARGIN
atom or number of number of number of
ion electrons neutrons protons
40Ca2+ 20 20
20

19F 9 9
9

10 9 8
[5]

(c) (i) The relative atomic mass, Ar, of an element is the average mass of its isotopes compared
to one atom of isotope X.



DO NOT WRITE IN THIS MARGIN
Identify isotope X.

..................................................................................................................................... [1]

(ii) A sample of magnesium consists of two isotopes with mass numbers 24 and 26.
[Ar: Mg, 24.3]

Calculate the percentage abundance of the isotope of magnesium with mass number 24.
DO NOT WRITE IN THIS MARGIN




percentage abundance = ......................................................... [1]

ĬÍĊ®Ġ´íÈõÏĪÅĊÞù·þ×
[Total: 9]
© UCLES 2025 ĬĄçúÙĞïďæüĆîĞô¶Ä÷Ă
ĥĕÕÕµµĥĕõõõÅąĕÅõĕÕ
0620/43/O/N/25

, * 0000800000003 * DFD
DO NOT WRITE IN THIS MARGIN



3
,










,

2 Table 2.1 shows the melting points, boiling points and electrical conductivities of seven substances,
A, B, C, D, E, F and G.

Table 2.1

melting point boiling point electrical conductivity electrical conductivity
substance
/ °C / °C when solid when molten
A 1600 2230 poor poor
B –219 –183 poor poor
DO NOT WRITE IN THIS MARGIN




C 770 1420 poor good
D –39 357 good good
E –7 58 poor poor
F 44 280 poor poor
G 1085 2562 good good

(a) Identify which substance, A, B, C, D, E, F or G, is:

(i) a gas at 25 °C
DO NOT WRITE IN THIS MARGIN




..................................................................................................................................... [1]

(ii) a solid consisting of simple molecules at 25 °C

..................................................................................................................................... [1]

(iii) a metal which is liquid at 25 °C.

..................................................................................................................................... [1]

(b) (i) Identify which substance, A, B, C, D, E, F or G, has a giant covalent structure.

Use the information in Table 2.1 to give two reasons for your choice.
DO NOT WRITE IN THIS MARGIN




substance ..........................................................................................................................

reason 1 .............................................................................................................................

reason 2 .............................................................................................................................
[3]

(ii) Identify which substance, A, B, C, D, E, F or G, is an ionic compound.

Use the information in Table 2.1 to give one reason for your choice.
DO NOT WRITE IN THIS MARGIN




substance ..........................................................................................................................

reason ................................................................................................................................
[2]

[Total: 8]

ĬÏĊ®Ġ´íÈõÏĪÅĊÞû·þ×
© UCLES 2025 ĬĄèùÑĬóğÓþû»ºČĢÄćĂ
ĥĕåĕõÕąõĥąåÅąõåµąÕ
0620/43/O/N/25 [Turn over