AQA AS Level Chemistry Paper 1
EXAM (updated 2026) Questions &
Answers | Latest Already Graded A+
UPDATE 2025|2026
What is the reaction mechanism associated most associated with Carbonyls? -
CORRECT ANSWERS-Nucleophilic Addition
What is the product when water is electrophilically added to an alkene? - CORRECT
ANSWERS-An alcohol
What is an elimination reaction? - CORRECT ANSWERS-One in which a small
molecule leaves the parent molecule
What is an alkene? - CORRECT ANSWERS-An unsaturated hydrocarbon
What is an unsaturated hydrocarbon? - CORRECT ANSWERS-A compound containing
only carbon and hydrogen atoms and containing at least one carbon carbon double
bond
What are van der Waals forces? - CORRECT ANSWERS-Relatively weak
intermolecular forces caused by temporary dipole dipole interaction
What is the general formula for an alkene? - CORRECT ANSWERS-CnH2n
How would you name an alkene given its displayed formula? - CORRECT ANSWERS-
Identify the longest carbon chain
Identify the position of the carbon carbon double bond
Identify any side chains
What are structural isomers? - CORRECT ANSWERS-Molecules with the same
molecular formula, but with different a structural formula
What are stereoisomers? - CORRECT ANSWERS-Molecules with the same molecular
AND structural formula but a different 3D arrangement of their atoms in space
What is E-Z isomerism? - CORRECT ANSWERS-The highest priority groups are on the
same side of the double bond
Describe the C=C double bond - CORRECT ANSWERS-Double covalent bond
,Planar bond
Area of high electron density
How do you assign the highest priority of groups in E-Z isomerism? - CORRECT
ANSWERS-The highest atomic number closest to the double bond has the highest
priority
If two groups have e.g. Only carbon and hydrogen, then the one with the most carbon
atoms is assigned the highest priority
What are Z isomers? - CORRECT ANSWERS-Molecules where the highest priority
groups are on the same side
What are E isomers? - CORRECT ANSWERS-Molecules where the highest priority
groups are on opposite sides
What is addition polymerisation? - CORRECT ANSWERS-The reaction by which
alkenes (or substituted alkenes) react with other alkene (or substituted alkene)
molecules to form polymers
What polymer would the monomer ethene form? - CORRECT ANSWERS-Poly(ethene)
What is a polymer? - CORRECT ANSWERS-A long chain of repeating monomer units
joined together
Why are addition polymers unreactive? - CORRECT ANSWERS-They lack the reactive
carbon-carbon double bond
Which is an area of high electron density
And so vulnerable to electrophilic attack
Why are the intermolecular forces between polymers often strong? - CORRECT
ANSWERS-Chains are often long
Many electrons
Many van der Waals'
Explain why a tertiary carbocation forms the major product and a secondary/primary
carbocation forms the minor product - CORRECT ANSWERS-Tertiary carbocation has
more alkyl groups attached
Positive inductive effect
Reduce + charge on carbon
More stable
Remains in reaction mixture for longer so more likely to react with electrophile
What is an electrophile? - CORRECT ANSWERS-A substance which can accept a pair
of electrons
(electron pair acceptor)
,What is a carbocation? - CORRECT ANSWERS-A species which contains a positive
charge on a carbon atom
Describe the mechanism by which HBr is added to ethene - CORRECT ANSWERS-e-'s
move from area of high electron density to delta + H
e-'s in H-Br bond move to delta - Br
Carbocation forms
Lone pair of e-'s on :Br- attracted to C+ HBr has been added across the double bond
Explain when major and minor products form in electrophilic addition to unsymmetrical
alkenes - CORRECT ANSWERS-Major product formed via carbocation which has most
alkyl groups bonded to it Minor product is formed via carbocation which has least alkyl
groups bonded to it Tertiary carbocation more stable than secondary more stable that
primary
How does the electrophile form in non-polar molecules such as Br2? - CORRECT
ANSWERS-When molecule moves close area of high electron density (C=C double
bond)
It becomes polarised
Electrons in C=C repel electrons in neutral molecule
Forms polar electrophile
Why are alkenes vulnerable to electrophilic attack? - CORRECT ANSWERS-Contain
C=C double bond
Area of high electron density
What is an addition reaction? - CORRECT ANSWERS-A reaction in which two
molecules join together to make one larger molecule
What is heterolytic fission? - CORRECT ANSWERS-Covalent bond breaks and both
electrons move to one atom.
Two oppositely charged ions are formed
What are produced by heterolytic fission? - CORRECT ANSWERS-Ions
What is a free radical? - CORRECT ANSWERS-An atom or group with an unpaired
electron, which is highly reactive as it wishes to pair up this electron
What is homolytic fission? - CORRECT ANSWERS-A reaction where each atom gets
one electron from the covalent bond
What are formed by homolytic fission? - CORRECT ANSWERS-Free radicals
What are the conditions needed for the chlorination of methane? - CORRECT
ANSWERS-UV Light or possibly heat
, What sort of reaction is the chlorination of methane? - CORRECT ANSWERS-Free
radical substitution
Why is the chlorination of methane a chain reaction? - CORRECT ANSWERS-Because
during the propagation step, one radical is produced for each one used
What reaction occurs during the initiation step of the chlorination of methane? -
CORRECT ANSWERS-Cl2 ----> 2Cl free radicals
What are the 3 steps of the chlorination of methane? - CORRECT ANSWERS-Initiation,
propagation, termination
What is a nucleophile? - CORRECT ANSWERS-An electron pair donor
What is the product of the nucleophilic substitution of a hydroxide into a haloalkane? -
CORRECT ANSWERS-An alcohol
What is the product of the nucleophilic substitution of a cyanide into a haloalkane? -
CORRECT ANSWERS-A nitrile
What is the reagent of the nucleophilic substitution of an ammonia into a haloalkane? -
CORRECT ANSWERS-Aqueous, alcoholic ammonia (in excess)
What can happen if nucleophilic substitution of ammonia occurs without excess
ammonia? - CORRECT ANSWERS-Further substitution, creating secondary or tertiary
amines or a quaternary ammonium salt
What is the difference between primary, secondary and tertiary amines? - CORRECT
ANSWERS-Primary has 1 carbon chain coming off, secondary 2, tertiary 3
What is a base? - CORRECT ANSWERS-A proton acceptor
What is the product of the nucleophilic elimination of an OH ion with a haloalkane? -
CORRECT ANSWERS-An alkene
Why does the strength of the carbon-halogen bond decrease as you go down the
group? - CORRECT ANSWERS-Because the atomic radius of the halogen increases as
you go down the group, so the area of the covalent bond also increases, making it
easier for electrons to be removed
Which type of carbocation is the most and which is the least stable? - CORRECT
ANSWERS-Tertiary is the most stable, methyl is the least stable
(1) Outline how to prepare a Standard Solution in a Volumetric Flask (for an acid-base
titration). - CORRECT ANSWERS-1. All apparatus rinsed with distilled water.
EXAM (updated 2026) Questions &
Answers | Latest Already Graded A+
UPDATE 2025|2026
What is the reaction mechanism associated most associated with Carbonyls? -
CORRECT ANSWERS-Nucleophilic Addition
What is the product when water is electrophilically added to an alkene? - CORRECT
ANSWERS-An alcohol
What is an elimination reaction? - CORRECT ANSWERS-One in which a small
molecule leaves the parent molecule
What is an alkene? - CORRECT ANSWERS-An unsaturated hydrocarbon
What is an unsaturated hydrocarbon? - CORRECT ANSWERS-A compound containing
only carbon and hydrogen atoms and containing at least one carbon carbon double
bond
What are van der Waals forces? - CORRECT ANSWERS-Relatively weak
intermolecular forces caused by temporary dipole dipole interaction
What is the general formula for an alkene? - CORRECT ANSWERS-CnH2n
How would you name an alkene given its displayed formula? - CORRECT ANSWERS-
Identify the longest carbon chain
Identify the position of the carbon carbon double bond
Identify any side chains
What are structural isomers? - CORRECT ANSWERS-Molecules with the same
molecular formula, but with different a structural formula
What are stereoisomers? - CORRECT ANSWERS-Molecules with the same molecular
AND structural formula but a different 3D arrangement of their atoms in space
What is E-Z isomerism? - CORRECT ANSWERS-The highest priority groups are on the
same side of the double bond
Describe the C=C double bond - CORRECT ANSWERS-Double covalent bond
,Planar bond
Area of high electron density
How do you assign the highest priority of groups in E-Z isomerism? - CORRECT
ANSWERS-The highest atomic number closest to the double bond has the highest
priority
If two groups have e.g. Only carbon and hydrogen, then the one with the most carbon
atoms is assigned the highest priority
What are Z isomers? - CORRECT ANSWERS-Molecules where the highest priority
groups are on the same side
What are E isomers? - CORRECT ANSWERS-Molecules where the highest priority
groups are on opposite sides
What is addition polymerisation? - CORRECT ANSWERS-The reaction by which
alkenes (or substituted alkenes) react with other alkene (or substituted alkene)
molecules to form polymers
What polymer would the monomer ethene form? - CORRECT ANSWERS-Poly(ethene)
What is a polymer? - CORRECT ANSWERS-A long chain of repeating monomer units
joined together
Why are addition polymers unreactive? - CORRECT ANSWERS-They lack the reactive
carbon-carbon double bond
Which is an area of high electron density
And so vulnerable to electrophilic attack
Why are the intermolecular forces between polymers often strong? - CORRECT
ANSWERS-Chains are often long
Many electrons
Many van der Waals'
Explain why a tertiary carbocation forms the major product and a secondary/primary
carbocation forms the minor product - CORRECT ANSWERS-Tertiary carbocation has
more alkyl groups attached
Positive inductive effect
Reduce + charge on carbon
More stable
Remains in reaction mixture for longer so more likely to react with electrophile
What is an electrophile? - CORRECT ANSWERS-A substance which can accept a pair
of electrons
(electron pair acceptor)
,What is a carbocation? - CORRECT ANSWERS-A species which contains a positive
charge on a carbon atom
Describe the mechanism by which HBr is added to ethene - CORRECT ANSWERS-e-'s
move from area of high electron density to delta + H
e-'s in H-Br bond move to delta - Br
Carbocation forms
Lone pair of e-'s on :Br- attracted to C+ HBr has been added across the double bond
Explain when major and minor products form in electrophilic addition to unsymmetrical
alkenes - CORRECT ANSWERS-Major product formed via carbocation which has most
alkyl groups bonded to it Minor product is formed via carbocation which has least alkyl
groups bonded to it Tertiary carbocation more stable than secondary more stable that
primary
How does the electrophile form in non-polar molecules such as Br2? - CORRECT
ANSWERS-When molecule moves close area of high electron density (C=C double
bond)
It becomes polarised
Electrons in C=C repel electrons in neutral molecule
Forms polar electrophile
Why are alkenes vulnerable to electrophilic attack? - CORRECT ANSWERS-Contain
C=C double bond
Area of high electron density
What is an addition reaction? - CORRECT ANSWERS-A reaction in which two
molecules join together to make one larger molecule
What is heterolytic fission? - CORRECT ANSWERS-Covalent bond breaks and both
electrons move to one atom.
Two oppositely charged ions are formed
What are produced by heterolytic fission? - CORRECT ANSWERS-Ions
What is a free radical? - CORRECT ANSWERS-An atom or group with an unpaired
electron, which is highly reactive as it wishes to pair up this electron
What is homolytic fission? - CORRECT ANSWERS-A reaction where each atom gets
one electron from the covalent bond
What are formed by homolytic fission? - CORRECT ANSWERS-Free radicals
What are the conditions needed for the chlorination of methane? - CORRECT
ANSWERS-UV Light or possibly heat
, What sort of reaction is the chlorination of methane? - CORRECT ANSWERS-Free
radical substitution
Why is the chlorination of methane a chain reaction? - CORRECT ANSWERS-Because
during the propagation step, one radical is produced for each one used
What reaction occurs during the initiation step of the chlorination of methane? -
CORRECT ANSWERS-Cl2 ----> 2Cl free radicals
What are the 3 steps of the chlorination of methane? - CORRECT ANSWERS-Initiation,
propagation, termination
What is a nucleophile? - CORRECT ANSWERS-An electron pair donor
What is the product of the nucleophilic substitution of a hydroxide into a haloalkane? -
CORRECT ANSWERS-An alcohol
What is the product of the nucleophilic substitution of a cyanide into a haloalkane? -
CORRECT ANSWERS-A nitrile
What is the reagent of the nucleophilic substitution of an ammonia into a haloalkane? -
CORRECT ANSWERS-Aqueous, alcoholic ammonia (in excess)
What can happen if nucleophilic substitution of ammonia occurs without excess
ammonia? - CORRECT ANSWERS-Further substitution, creating secondary or tertiary
amines or a quaternary ammonium salt
What is the difference between primary, secondary and tertiary amines? - CORRECT
ANSWERS-Primary has 1 carbon chain coming off, secondary 2, tertiary 3
What is a base? - CORRECT ANSWERS-A proton acceptor
What is the product of the nucleophilic elimination of an OH ion with a haloalkane? -
CORRECT ANSWERS-An alkene
Why does the strength of the carbon-halogen bond decrease as you go down the
group? - CORRECT ANSWERS-Because the atomic radius of the halogen increases as
you go down the group, so the area of the covalent bond also increases, making it
easier for electrons to be removed
Which type of carbocation is the most and which is the least stable? - CORRECT
ANSWERS-Tertiary is the most stable, methyl is the least stable
(1) Outline how to prepare a Standard Solution in a Volumetric Flask (for an acid-base
titration). - CORRECT ANSWERS-1. All apparatus rinsed with distilled water.
