Please check the examination details below before entering your candidate information
Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel International Advanced Level
Wednesday 6 May 2026 Mark Scheme (Results)
Afternoon (Time: 1 hour 30 minutes) Paper
reference WCH11/01
Chemistry
International Advanced Subsidiary/Advanced Level
UNIT 1: Structure, Bonding and Introduction to Summer 2026
Organic Chemistry
You must have: Total Marks
Scientific calculator Pearson Edexcel International Advanced
Subsidiary Level In Chemistry
Instructions
WCH11/01
•• Use black ink or ball-point pen.
If pencil is used for diagrams/sketches/graphs it must be dark (HB or B).
• Fill in the boxes at the top of this page with your name,
centre number and candidate number.
•• Answer allthequestions.
Answer
questions in the spaces provided
– there may be more space than you need.
Information
•• The total mark for this paper is 80.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
• You will be assessed on your ability to organise and present information, ideas,
descriptions and arguments clearly and logically, including your use of grammar,
punctuation and spelling.
• A Periodic Table is printed on the back cover of this paper.
Advice
•• Read each question carefully before you start to answer it.
Show all your working in calculations and include units where appropriate.
•• Try to answer every question.
Check your answers if you have time at the end. Turn over
P79218APearson Education Ltd.
P:1/1/1/1/1/
*P79218A0124*
, SECTION A
Edexcel and BTEC Qualifications
Answer ALL the questions in this section.
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
You should aim to spend no more than 20 minutes on this section. Edexcel and BTEC qualifications are awarded by Pearson, the UK’s
For each question, select one answer from A to D and put a cross in the box . If you change largest awarding body. We provide a wide range of qualifications
your mind, put a line through the box and then mark your new answer with a cross . including academic, vocational, occupational and specific
programmes for employers. For further information visit our
1 How many atoms are there in 17.0 g of hydrogen peroxide, H2O2 ?
qualifications websites at or .
[Data: Avogadro constant, L = 6.02 × 1023 mol−1] Alternatively, you can get in touch with us using the details on our
contact us page at
A 3.01 × 1023
B 6.02 × 1023
C 1.20 × 1024
D 2.41 × 1024
(Total for Question 1 = 1 mark)
Pearson: helping people progress, everywhere
2 A sample of gas was prepared for use in helium-neon lasers.
The sample contained 5.0 g of helium and 5.0 g of neon. Pearson aspires to be the world’s leading learning company. Our aim is to help everyone
progress in their lives through education. We believe in every kind of learning, for all kinds
What is the ratio of helium atoms to neon atoms in the sample? of people, wherever they are in the world. We’ve been involved in education for over 150
[Data: Ar values He = 4.0 Ne = 20.2] years, and by working across 70 countries, in 100 languages, we have built an
international reputation for our commitment to high standards and raising achievement
A 1:1 through innovation in education. Find out more about how we can help you and your
students at:
B 5:2
C 1:5
D 5:1
(Total for Question 2 = 1 mark)
3 A sample of 5.72 g of hydrated sodium carbonate, Na2CO3•10H2O , was dissolved in
deionised water to form 250 cm3 of solution.
What is the concentration, in mol dm−3, of the solution formed?
Summer 2026
[Data: Ar values H = 1.0 C = 12.0 O = 16.0 Na = 23.0] Question Paper Log Number P79218A
Publication Code WCH11_01_2606_MS
A 0.020
All the material in this publication is
B 0.080 Pearson Education Ltd
C 0.054
D 0.220
(Total for Question 3 = 1 mark)
2
*P79218A0224*
, General Marking Guidance
4 The element iron has the atomic number Z = 26.
What are the numbers of s, p and d electrons in an Fe2+ ion? • All candidates must receive the same treatment. Examiners must mark the first
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
candidate in exactly the same way as they mark the last.
s electrons p electrons d electrons • Mark schemes should be applied positively. Candidates must be rewarded for
A what they have shown they can do rather than penalised for omissions.
B • Examiners should mark according to the mark scheme not according to their
perception of where the grade boundaries may lie.
C
• There is no ceiling on achievement. All marks on the mark scheme should be
D used appropriately.
(Total for Question 4 = 1 mark) • All the marks on the mark scheme are designed to be awarded. Examiners
should always award full marks if deserved, i.e. if the answer matches the mark
79 81
5 A sample of bromine contains two isotopes, Br and Br. scheme. Examiners should also be prepared to award zero marks if the
Which m / z peaks due to singly-charged ions will be in the mass spectrum of candidate’s response is not worthy of credit according to the mark scheme.
this sample? • Where some judgement is required, mark schemes will provide the principles by
which marks will be awarded and exemplification may be limited.
A 79 and 81 only
• When examiners are in doubt regarding the application of the mark scheme to a
B 79, 81 and 160 only
candidate’s response, the team leader must be consulted.
C 79, 81, 158 and 162 only • Crossed out work should be marked UNLESS the candidate has replaced it with
D 79, 81, 158, 160 and 162 an alternative response.
(Total for Question 5 = 1 mark)
6 The two electrons in a 1s orbital are represented by arrows pointing in
opposite directions.
Why are the electrons represented in this way?
A electrons in the same orbital have opposite spins
B electrons move round the nucleus in opposite directions
C the 1s orbital of an atom has the lowest energy
D the electrons in the orbital have different energies
(Total for Question 6 = 1 mark)
Use this space for any rough working. Anything you write in this space will gain no credit.
3
*P79218A0324* Turn over
Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel International Advanced Level
Wednesday 6 May 2026 Mark Scheme (Results)
Afternoon (Time: 1 hour 30 minutes) Paper
reference WCH11/01
Chemistry
International Advanced Subsidiary/Advanced Level
UNIT 1: Structure, Bonding and Introduction to Summer 2026
Organic Chemistry
You must have: Total Marks
Scientific calculator Pearson Edexcel International Advanced
Subsidiary Level In Chemistry
Instructions
WCH11/01
•• Use black ink or ball-point pen.
If pencil is used for diagrams/sketches/graphs it must be dark (HB or B).
• Fill in the boxes at the top of this page with your name,
centre number and candidate number.
•• Answer allthequestions.
Answer
questions in the spaces provided
– there may be more space than you need.
Information
•• The total mark for this paper is 80.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
• You will be assessed on your ability to organise and present information, ideas,
descriptions and arguments clearly and logically, including your use of grammar,
punctuation and spelling.
• A Periodic Table is printed on the back cover of this paper.
Advice
•• Read each question carefully before you start to answer it.
Show all your working in calculations and include units where appropriate.
•• Try to answer every question.
Check your answers if you have time at the end. Turn over
P79218APearson Education Ltd.
P:1/1/1/1/1/
*P79218A0124*
, SECTION A
Edexcel and BTEC Qualifications
Answer ALL the questions in this section.
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
You should aim to spend no more than 20 minutes on this section. Edexcel and BTEC qualifications are awarded by Pearson, the UK’s
For each question, select one answer from A to D and put a cross in the box . If you change largest awarding body. We provide a wide range of qualifications
your mind, put a line through the box and then mark your new answer with a cross . including academic, vocational, occupational and specific
programmes for employers. For further information visit our
1 How many atoms are there in 17.0 g of hydrogen peroxide, H2O2 ?
qualifications websites at or .
[Data: Avogadro constant, L = 6.02 × 1023 mol−1] Alternatively, you can get in touch with us using the details on our
contact us page at
A 3.01 × 1023
B 6.02 × 1023
C 1.20 × 1024
D 2.41 × 1024
(Total for Question 1 = 1 mark)
Pearson: helping people progress, everywhere
2 A sample of gas was prepared for use in helium-neon lasers.
The sample contained 5.0 g of helium and 5.0 g of neon. Pearson aspires to be the world’s leading learning company. Our aim is to help everyone
progress in their lives through education. We believe in every kind of learning, for all kinds
What is the ratio of helium atoms to neon atoms in the sample? of people, wherever they are in the world. We’ve been involved in education for over 150
[Data: Ar values He = 4.0 Ne = 20.2] years, and by working across 70 countries, in 100 languages, we have built an
international reputation for our commitment to high standards and raising achievement
A 1:1 through innovation in education. Find out more about how we can help you and your
students at:
B 5:2
C 1:5
D 5:1
(Total for Question 2 = 1 mark)
3 A sample of 5.72 g of hydrated sodium carbonate, Na2CO3•10H2O , was dissolved in
deionised water to form 250 cm3 of solution.
What is the concentration, in mol dm−3, of the solution formed?
Summer 2026
[Data: Ar values H = 1.0 C = 12.0 O = 16.0 Na = 23.0] Question Paper Log Number P79218A
Publication Code WCH11_01_2606_MS
A 0.020
All the material in this publication is
B 0.080 Pearson Education Ltd
C 0.054
D 0.220
(Total for Question 3 = 1 mark)
2
*P79218A0224*
, General Marking Guidance
4 The element iron has the atomic number Z = 26.
What are the numbers of s, p and d electrons in an Fe2+ ion? • All candidates must receive the same treatment. Examiners must mark the first
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
candidate in exactly the same way as they mark the last.
s electrons p electrons d electrons • Mark schemes should be applied positively. Candidates must be rewarded for
A what they have shown they can do rather than penalised for omissions.
B • Examiners should mark according to the mark scheme not according to their
perception of where the grade boundaries may lie.
C
• There is no ceiling on achievement. All marks on the mark scheme should be
D used appropriately.
(Total for Question 4 = 1 mark) • All the marks on the mark scheme are designed to be awarded. Examiners
should always award full marks if deserved, i.e. if the answer matches the mark
79 81
5 A sample of bromine contains two isotopes, Br and Br. scheme. Examiners should also be prepared to award zero marks if the
Which m / z peaks due to singly-charged ions will be in the mass spectrum of candidate’s response is not worthy of credit according to the mark scheme.
this sample? • Where some judgement is required, mark schemes will provide the principles by
which marks will be awarded and exemplification may be limited.
A 79 and 81 only
• When examiners are in doubt regarding the application of the mark scheme to a
B 79, 81 and 160 only
candidate’s response, the team leader must be consulted.
C 79, 81, 158 and 162 only • Crossed out work should be marked UNLESS the candidate has replaced it with
D 79, 81, 158, 160 and 162 an alternative response.
(Total for Question 5 = 1 mark)
6 The two electrons in a 1s orbital are represented by arrows pointing in
opposite directions.
Why are the electrons represented in this way?
A electrons in the same orbital have opposite spins
B electrons move round the nucleus in opposite directions
C the 1s orbital of an atom has the lowest energy
D the electrons in the orbital have different energies
(Total for Question 6 = 1 mark)
Use this space for any rough working. Anything you write in this space will gain no credit.
3
*P79218A0324* Turn over
