0620 w17 ms 41 - Best Exam Help
Cambridge Assessment International Education Cambridge International General Certificate of Secondary Education
CHEMISTRY Paper 4 Extended Theory MARK SCHEME Maximum Mark: 80
0620/41 October/November 2017
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners' meeting before marking began, which would have considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the October/November 2017 series for most Cambridge IGCSE?, Cambridge International A and AS Level components and some Cambridge O Level components.
? IGCSE is a registered trademark. This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 8 printed pages.
? UCLES 2017
[Turn over
0620/41
Question
1(a)(i) B
1(a)(ii) A
1(a)(iii) C
1(a)(iv) 1(b)
E
O2? M1 O M2 2?
Cambridge IGCSE ? Mark Scheme PUBLISHED
Answer
Question
Answer
2(a)(i) S
2(a)(ii) S
2(a)(iii) V
2(b)
any value in the range 130?145?C
2(c) sublimation
2(d)(i) 2(d)(ii)
Brownian motion nitrogen/oxygen/carbon dioxide/air molecules hit/bombard the smoke particles
(the bombarding particles) move randomly
? UCLES 2017
Page 2 of 8
October/November 2017
Marks 1 1 1 1 2
Marks 1 1 1 1 1 1 1 1
0620/41 Question
Cambridge IGCSE ? Mark Scheme PUBLISHED
Answer
3(a)(i) brown/orange solid (forms/is made) OR solution becomes paler/colourless
3(a)(ii)
magnesium is oxidised AND copper ions are reduced OR magnesium loses electrons AND copper ions gain electrons OR magnesium increases in oxidation number AND copper decreases in oxidation number
3(a)(iii) Cu2+ OR copper(II) ions OR copper ions
gains electrons
3(a)(iv) 3(b)(i)
3Mg + Fe2O3 3MgO + 2Fe M1 Fe2O3 AND MgO M2 fully correct
prevents air/oxygen AND water from reaching the steel
3(b)(ii) magnesium is more reactive than iron/steel
the magnesium corrodes (before the iron/steel) OR the magnesium corrodes preferentially
3(b)(iii) copper is less reactive than iron/steel
October/November 2017
Marks 1 1
1 1 2
1 1 1
1
? UCLES 2017
Page 3 of 8
0620/41
Question
4(a)(i)
2(C2H5OH) + 2CO2 M1 carbon dioxide made as product M2 balanced
Cambridge IGCSE ? Mark Scheme PUBLISHED
Answer
4(a)(ii)
any 2 from:
? 37 ?C ? anaerobic ? glucose is aqueous ? yeast
4(b)(i) (concentrated) phosphoric acid
4(b)(ii) 4(c)(i)
92 If full credit is not awarded, allow 1 mark for Mr of ethene = 28
(acidified) potassium manganate(VII) OR potassium (di)chromate(VI)
4(c)(ii)
October/November 2017
Marks 2
2
1 2 1 3
M1 all shared pairs of electrons correct for single bonds M2 2 shared pairs of electrons for the C=O bond M3 total of 8 electrons on each O including 4 non-bonding electrons and no additional non-bonding electrons
4(d)(i) partially ionised/dissociated
1
? UCLES 2017
Page 4 of 8
0620/41 Question
Cambridge IGCSE ? Mark Scheme PUBLISHED
Answer
4(d)(ii) M1 (acids) have same concentration
M2: measure pH OR describe how to measure pH (such as use Universal Indicator) M3: lower pH corresponds to the stronger acid/hydrochloric acid
OR M2: add calcium/magnesium/zinc/iron M3: faster rate of forming bubbles corresponds to the stronger acid/hydrochloric acid
OR
M2: rate of reaction with (metal) carbonate M3: faster rate of forming bubbles corresponds to the stronger acid/hydrochloric acid
OR
M2: rate of reaction with (named) metal oxide M3: dissolves faster means that reaction is with the stronger acid/hydrochloric acid
OR
M2: electrical conductivity M3: greater conductivity corresponds to the stronger acid/hydrochloric acid
OR
M2: add sodium hydroxide (or other named alkali) M3: greater temperature change corresponds to the stronger acid/hydrochloric acid
4(e) structure of propanoic acid
propanoic acid
structure of butan-1-ol
butan-1-ol
? UCLES 2017
Page 5 of 8
October/November 2017
Marks 1 2
1 1 1 1
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