* 0000800000001 * DFD
, ,
Cambridge IGCSE™
¬O. 4mHuOªE^z6W
¬XrY¤¨]ouUt1zq
¥5eU55eU e EUE5U
* 1 1 9 1 6 4 9 6 3 2 *
CHEMISTRY 0620/42
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/SW) 347745/3
© UCLES 2025 [Turn over
, * 0000800000002 * DFD
DO NOT WRITE IN THIS MARGIN
2
, ,
1 The three states of matter are solid, liquid and gas.
(a) Complete Table 1.1 to describe the structures of solids, liquids and gases in terms of
particle separation, particle arrangement and particle motion.
Table 1.1
state of matter particle separation particle arrangement particle motion
DO NOT WRITE IN THIS MARGIN
solid touching
liquid
gas random random
[3]
(b) Substances can physically change.
Name each physical change:
DO NOT WRITE IN THIS MARGIN
• solid to liquid ......................................................................................................................
• gas to liquid ........................................................................................................................
• solid to aqueous. ................................................................................................................
[3]
(c) Gases diffuse.
(i) Describe, in terms of particles, why gases diffuse.
..................................................................................................................................... [1]
DO NOT WRITE IN THIS MARGIN
(ii) State what determines the relative rate of diffusion of gases at constant temperature.
..................................................................................................................................... [1]
(d) Gaseous oxides of nitrogen are atmospheric pollutants. One adverse effect of oxides of
nitrogen is the formation of acid rain.
State two other adverse effects of oxides of nitrogen.
1 .................................................................................................................................................
2 .................................................................................................................................................
DO NOT WRITE IN THIS MARGIN
[2]
ĬÍĊ®Ġ´íÈõÏĪÅĊßü¸þ×
© UCLES 2025 ĬċÖñÜĨĤĝÖĂăºÌĩāÂùĂ
ĥĥµÕõÕĥµµĥÕÅÅĕåÕĕÕ
0620/42/O/N/25
, * 0000800000003 * DFD
DO NOT WRITE IN THIS MARGIN
3
, ,
(e) In a catalytic converter, oxides of nitrogen are removed by reaction with the toxic gaseous
product of the incomplete combustion of hydrocarbon fuels. Two non-toxic gases are formed
in this reaction.
(i) Name the toxic gaseous product of the incomplete combustion of hydrocarbon fuels.
..................................................................................................................................... [1]
(ii) Name the two non-toxic gases formed in the catalytic converter.
1 .........................................................................................................................................
DO NOT WRITE IN THIS MARGIN
2 .........................................................................................................................................
[2]
[Total: 13]
DO NOT WRITE IN THIS MARGIN
DO NOT WRITE IN THIS MARGIN
DO NOT WRITE IN THIS MARGIN
ĬÏĊ®Ġ´íÈõÏĪÅĊßú¸þ×
© UCLES 2025 ĬċÕòÔĢĠčãøîïĐđÕÂĉĂ
ĥĥÅĕµµąÕåĕąÅÅõÅĕąÕ
0620/42/O/N/25 [Turn over
, ,
Cambridge IGCSE™
¬O. 4mHuOªE^z6W
¬XrY¤¨]ouUt1zq
¥5eU55eU e EUE5U
* 1 1 9 1 6 4 9 6 3 2 *
CHEMISTRY 0620/42
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/SW) 347745/3
© UCLES 2025 [Turn over
, * 0000800000002 * DFD
DO NOT WRITE IN THIS MARGIN
2
, ,
1 The three states of matter are solid, liquid and gas.
(a) Complete Table 1.1 to describe the structures of solids, liquids and gases in terms of
particle separation, particle arrangement and particle motion.
Table 1.1
state of matter particle separation particle arrangement particle motion
DO NOT WRITE IN THIS MARGIN
solid touching
liquid
gas random random
[3]
(b) Substances can physically change.
Name each physical change:
DO NOT WRITE IN THIS MARGIN
• solid to liquid ......................................................................................................................
• gas to liquid ........................................................................................................................
• solid to aqueous. ................................................................................................................
[3]
(c) Gases diffuse.
(i) Describe, in terms of particles, why gases diffuse.
..................................................................................................................................... [1]
DO NOT WRITE IN THIS MARGIN
(ii) State what determines the relative rate of diffusion of gases at constant temperature.
..................................................................................................................................... [1]
(d) Gaseous oxides of nitrogen are atmospheric pollutants. One adverse effect of oxides of
nitrogen is the formation of acid rain.
State two other adverse effects of oxides of nitrogen.
1 .................................................................................................................................................
2 .................................................................................................................................................
DO NOT WRITE IN THIS MARGIN
[2]
ĬÍĊ®Ġ´íÈõÏĪÅĊßü¸þ×
© UCLES 2025 ĬċÖñÜĨĤĝÖĂăºÌĩāÂùĂ
ĥĥµÕõÕĥµµĥÕÅÅĕåÕĕÕ
0620/42/O/N/25
, * 0000800000003 * DFD
DO NOT WRITE IN THIS MARGIN
3
, ,
(e) In a catalytic converter, oxides of nitrogen are removed by reaction with the toxic gaseous
product of the incomplete combustion of hydrocarbon fuels. Two non-toxic gases are formed
in this reaction.
(i) Name the toxic gaseous product of the incomplete combustion of hydrocarbon fuels.
..................................................................................................................................... [1]
(ii) Name the two non-toxic gases formed in the catalytic converter.
1 .........................................................................................................................................
DO NOT WRITE IN THIS MARGIN
2 .........................................................................................................................................
[2]
[Total: 13]
DO NOT WRITE IN THIS MARGIN
DO NOT WRITE IN THIS MARGIN
DO NOT WRITE IN THIS MARGIN
ĬÏĊ®Ġ´íÈõÏĪÅĊßú¸þ×
© UCLES 2025 ĬċÕòÔĢĠčãøîïĐđÕÂĉĂ
ĥĥÅĕµµąÕåĕąÅÅõÅĕąÕ
0620/42/O/N/25 [Turn over
