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This is the final mark scheme graded A+
Typology: Exams
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A level
Version: 1.0 Final
1. General
The mark scheme for each question shows:
the marks available for each part of the question
the total marks available for the question
the typical answer or answers which are expected
extra information to help the examiner make his or her judgement and help to delineate what
is acceptable or not worthy of credit or, in discursive answers, to give an overview of the area
in which a mark or marks may be awarded.
The extra information in the ‘Comments’ column is aligned to the appropriate answer in the
left-hand part of the mark scheme and should only be applied to that item in the mark scheme.
You should mark according to the contents of the mark scheme. If you are in any doubt about
applying the mark scheme to a particular response, consult your Team Leader.
At the beginning of a part of a question a reminder may be given, for example: where
consequential marking needs to be considered in a calculation; or the answer may be on the
diagram or at a different place on the script.
In general the right-hand side of the mark scheme is there to provide those extra details which
might confuse the main part of the mark scheme yet may be helpful in ensuring that marking is
straightforward and consistent.
The use of M1, M2, M3 etc in the right-hand column refers to the marking points in the order in
which they appear in the mark scheme. So, M1 refers to the first marking point, M2 the second
marking point etc.
For example, in a question requiring 2 answers for 2 marks:
Correct
answers
Incorrect
answers (ie
incorrect rather
than neutral)
Mark (2) Comment
They have not exceeded the maximum
number of responses so there is no
penalty.
They have exceeded the maximum number
of responses so the extra incorrect
response cancels the correct one.
3 0 2 The maximum mark is 2
The incorrect response cancels out one of
the two correct responses that gained
credit.
Two incorrect responses cancel out the two
marks gained.
3.2 Marking procedure for calculations
Full marks should be awarded for a correct numerical answer, without any working
shown, unless the question states ‘Show your working’ or ‘justify your answer’. In this
case, the mark scheme will clearly indicate what is required to gain full credit.
If an answer to a calculation is incorrect and working is shown, process mark(s) can
usually be gained by correct substitution / working and this is shown in the ‘Comments’
column or by each stage of a longer calculation.
3.3 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are most likely to be restricted to calculation
questions and should be shown by the abbreviation ECF or consequential in the marking
scheme.
An arithmetic error should be penalised for one mark only unless otherwise amplified in
the marking scheme. Arithmetic errors may arise from a slip in a calculation or from an
incorrect transfer of a numerical value from data given in a question.
3.4 Equations
In questions requiring students to write equations, state symbols are generally ignored
unless otherwise stated in the ‘Comments’ column.
Examiners should also credit correct equations using multiples and fractions unless
otherwise stated in the ‘Comments’ column.
3.5 Oxidation states
In general, the sign for an oxidation state will be assumed to be positive unless
specifically shown to be negative.
3.6 Interpretation of ‘it’
Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the
correct subject.
3.7 Phonetic spelling
The phonetic spelling of correct scientific terminology should be credited unless there is a
possible confusion with another technical term or if the question requires correct IUPAC
nomenclature.
3.8 Brackets
(…..) are used to indicate information which is not essential for the mark to be awarded
but is included to help the examiner identify the sense of the answer required.
3.9 Ignore / Insufficient / Do not allow
Ignore or insufficient is used when the information given is irrelevant to the question or not
enough to gain the marking point. Any further correct amplification could gain the marking
point.
Do not allow means that this is a wrong answer which, even if the correct answer is
given, will still mean that the mark is not awarded.
3.10 Marking crossed out work
Crossed out work that has not been replaced should be marked as if it were not crossed
out, if possible. Where crossed out work has been replaced, the replacement work and
not the crossed out work should be marked.
3.11 Reagents
The command word ‘Identify’, allows the student to choose to use either the name or the
formula of a reagent in their answer. In some circumstances, the list principle may apply
when both the name and the formula are used. Specific details will be given in mark
schemes.
The guiding principle is that a reagent is a chemical which can be taken out of a bottle or
container. Failure to identify complete reagents will be penalised , but follow-on marks
(eg for a subsequent equation or observation) can be scored from an incorrect attempt
(possibly an incomplete reagent) at the correct reagent. Specific details will be given in
mark schemes.
For example, no credit would be given for:
By way of illustration, the following would apply.
not allowed not allowed not allowed not allowed not allowed
not allowed not allowed not allowed not allowed not allowed
Representation^ of^ CH 2 by^ CH 2 will^ be^ penalised
Some examples are given here of structures for specific compounds that should not
gain credit (but, exceptions may be made in the context of balancing equations)
CH 3 COH for ethanal
CH 3 CH 2 HO for ethanol
OHCH 2 CH 3 for ethanol
C 2 H 6 O for ethanol
CH 2 CH 2 for ethene
CH 2. CH 2 for ethene
CH 2 : CH 2 for ethene
Each of the following should gain credit as alternatives to correct representations of
the structures.
CH 2 = CH 2 for ethene, H 2 C=CH 2
CH 3 CHOHCH 3 for propan- 2 - ol, CH 3 CH(OH)CH 3
In most cases, the use of ‘sticks’ to represent C ─ H bonds in a structure should not be
penalised. The exceptions to this when “sticks” will be penalised include
structures in mechanisms where the C ─ H bond is essential (eg elimination
reactions in halogenoalkanes and alcohols)
when a displayed formula is required
when a skeletal structure is required or has been drawn by the candidate.
3.13 Organic names
As a general principle, non-IUPAC names or incorrect spelling or incomplete names
should not gain credit. Some illustrations are given here.
Unnecessary but not wrong numbers will not be penalised such as the number ‘2’ in 2 -
methylpropane or the number ‘1’ in 2 - chlorobutan- 1 - oic acid.
but- 2 - ol should be butan- 2 - ol
2 - hydroxybutane should be butan- 2 - ol
butane- 2 - ol should be butan- 2 - ol
2 - butanol should^ be^ butan-^2 - ol
ethan-1,2-diol should be ethane-1,2-diol
2 - methpropan- 2 - ol should be 2 - methylpropan- 2 - ol
2 - methylbutan- 3 - ol should^ be^^3 - methylbutan-^2 - ol
3 - methylpentan should be 3 - methylpentane
3 - mythylpentane should be 3 - methylpentane
3 - methypentane should^ be^^3 - methylpentane
propanitrile should be propanenitrile
aminethane should be ethylamine (although aminoethane can gain credit)
2 - methyl- 3 - bromobutane should be 2 - bromo- 3 - methylbutane
3 - bromo- 2 - methylbutane should be 2 - bromo- 3 - methylbutane
3 - methyl- 2 - bromobutane should^ be^^2 - bromo-^3 - methylbutane
2 - methylbut- 3 - ene should be 3 - methylbut- 1 - ene
difluorodichloromethane should be dichlorodifluoromethane
When assigning a level you should look at the overall quality of the answer and not look to pick
holes in small and specific parts of the answer where the student has not performed quite as well
as the rest. If the answer covers different aspects of different levels of the mark scheme you
should use a best fit approach for defining the level.
Once the level has been decided, the mark within the level is determined by the communication
statement:
the level.
within the level.
The exemplar materials used during standardisation will help you to determine the appropriate
level. There will be an exemplar in the standardising materials which will correspond with each
level of the mark scheme and for each mark within each level. This answer will have been
awarded a mark by the Lead Examiner. You can compare the student’s answer with the
exemplar to determine if it is the same standard, better or worse than the example. You can then
use this to allocate a mark for the answer based on the Lead Examiner’s mark on the exemplar.
You may well need to read back through the answer as you apply the mark scheme to clarify
points and assure yourself that the level and the mark are appropriate.
Indicative content in the mark scheme is provided as a guide for examiners. It is not intended to
be exhaustive and you must credit other chemically valid points. Students may not have to cover
all of the points mentioned in the indicative content to reach the highest level of the mark scheme.
The mark scheme will state how much chemical content is required for the highest level.
An answer which contains nothing of relevance to the question must be awarded no marks.
For other extended response answers:
Where a mark scheme includes linkage words (such as ‘therefore’, ‘so’, ‘because’ etc), these are
optional. However, a student’s marks for the question may be limited if they do not demonstrate
the ability to construct and develop a sustained line of reasoning which is coherent, relevant,
substantiated and logically structured. In particular answers in the form of bullet pointed lists may
not be awarded full marks if there is no indication of logical flow between each point or if points
are in an illogical order.
The mark schemes for some questions state that the maximum mark available for an extended
response answer is limited if the answer is not coherent, relevant, substantiated and logically
structured. During the standardisation process, the Lead Examiner will provide marked exemplar
material to demonstrate answers which have not met these criteria. You should use these
Question (^) Answers Additional comments/Guidelines Mark
B/ Boron
any 2 from:
protons in the centre of the atom/nucleus
electrons are in shells/energy levels (around the nucleus)
neutrons in the centre of the atom/nucleus
most of the atom is empty space/most of mass in nucleus
(3 x AO1)
Question Answers Additional comments/Guidelines Mark
Definition
Average / mean mass of 1 atom (of an element) (1)
1/12 mass of one atom of
12 C (1)
Or
Average / mean mass of atoms of an element
1/12 mass of one atom of
12 C
11
Or
I has similar chemistry/chemical properties to other Group 7
elements
Question Answers Additional comments/Guidelines Mark
Te(g) + e
(g) + 2 e
Or
Te(g) → Te
(g) + e
(1 x AO1)
Question Answers Additional comments/Guidelines Mark
M1 v = d^ = 4.17 × 10
6 (m s
t
2 −
M2 m =
2KE×t or m =
2KE or
2 𝑥 1.88 𝑥 10
d^2 v^2 (4.17 𝑥 106 )
2
M3 m = 2.16 x 10
M4 mass of 1 mole of ions = L × 1000 × M3 = 130.4 (g)
M5 y = 130 or 131
M4 Allow 130 to 131 (3 or more significant
figures)
M5 Must be an integer
(4 x AO2,
1 x AO3)
Question Answers Additional comments/Guidelines Mark
01.5 The KE of
126 Te
is the same as the KE of
124 Te
(1 x AO1)
Question Answers Additional comments/Guidelines Mark
To prevent reaction with carbon dioxide (in the air)
To prevent evaporation (of water/from solution)
Allow so flask can inverted/shaken (to ensure
homogeneous mixture)
Ignore contamination
(1 x AO2)
Question Answers Additional comments/Guidelines Mark
Answer C 1
(1 x AO3)
Question Answers Additional comments/Guidelines Mark
M1 Sr(OH) 2 + 2 HCl → SrCl 2 + 2 H 2 O
M2 32.43 (cm
3 )
M3 n HCl in mean titre = 3.24(3) × 10
M4 n Sr(OH) 2 in 25 cm
3 = 1.62 × 10
M5 n Sr(OH) 2 in 100 cm
3 of solution = 6.48 × 10
M6 mass = (6.48×
3
solution)
M1 Equation
M2 allow 32.
M3 allow 0.1 x M2 ÷ 1000
M4 allow M3 ÷ 2
M5 allow M4 × 4
M6 allow = M5 × 121.
M6 allow 0.
allow M5 and M6 in either order
(6 x AO2)
Question Answers Additional comments/Guidelines Mark
This question is marked using levels of response. Refer to
the Mark Scheme Instructions for Examiners for guidance on
how to mark this question.
Level 3
5 – 6 marks
All stages are covered and the description of each stage is
generally correct and virtually complete.
Answer is communicated coherently and shows a logical
progression from stage 1 to stage 2 and stage 3.
Level 2
3 – 4 marks
All stages are covered but the description of each stage may
be incomplete or may contain inaccuracies OR two stages are
covered and the explanations are generally correct and
virtually complete.
Answer is mainly coherent and shows progression from stage
1 to stage 2 and/or stage 3.
Level 1
1 – 2 marks
Two stages are covered but the description of each stage
may be incomplete or may contain inaccuracies, OR only one
stage is covered but the explanation is generally correct and
virtually complete.
Answer includes isolated statements and these are presented
in a logical order.
Level 0
0 marks
Insufficient correct chemistry to gain a mark.
Indicative Chemistry Content
stage 1
1a labelled axes
and concentration (of S 2 O
2 – ions) decreasing with 8
time (ignore units)
1b downwards curve of reducing steepness
2 x AO2, 2
x AO3)
stage 2 explanation
2 – –
Ea
Or
(reaction slow) because two negative ions repel/high
Ea
2 –
2b Fe
2+ attracts the S 2 O 8 so lower Ea
Or 2 –
Fe
2+ and S 2 O 8 oppositely charged so lower Ea
2c Iron/Fe has a variable oxidation state
Or
Fe
2+ oxidised to Fe
3+
Or
Fe
2+ Fe
3+
stage 3 equations
2 – 2 – 3+
3a 2 Fe
2+
3b 2 Fe
3+
2+
2 – – 2 –
allow equations with hexaaqua ions