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Cambridge IGCSE™
*9534637521*
CHEMISTRY 0620/43
Paper 4 Theory (Extended) May/June 2023
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.
IB23 06_0620_43/2RP
© UCLES 2023 [Turn over
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2
1 Some symbol equations and word equations, A to J, are shown.
A H+ + OH– → H2O
B Cr3+ + 3OH– → Cr(OH)3
C methane + chlorine → chloromethane + hydrogen chloride
D propene + bromine → 1,2-dibromopropane
E C10H22 → C8H18 + C2H4
F chlorine + aqueous potassium bromide → bromine + aqueous potassium chloride
G methane + oxygen → carbon monoxide + water
H C2H5COOH + CH3OH → C2H5COOCH3 + H2O
I hydrogen + oxygen → water
J 6CO2 + 6H2O → C6H12O6 + 6O2
Use the equations to answer the questions that follow.
Each equation may be used once, more than once, or not at all.
Give the letter, A to J, for the equation which represents:
(a) photosynthesis ..................................................................................................................... [1]
(b) an addition reaction ............................................................................................................. [1]
(c) a precipitation reaction ........................................................................................................ [1]
(d) incomplete combustion ........................................................................................................ [1]
(e) a displacement reaction ....................................................................................................... [1]
(f) a substitution reaction. ......................................................................................................... [1]
[Total: 6]
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3
Question 2 starts on the next page.
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4
2 (a) The symbols of the elements in Period 3 of the Periodic Table are shown.
Na Mg Al Si P S Cl Ar
Use the symbols of the elements in Period 3 to answer the questions that follow.
Each symbol may be used once, more than once, or not at all.
Give the symbol of the element that:
(i) is present in purified bauxite ......................................................................................... [1]
(ii) contains atoms with a full outer shell of electrons ........................................................ [1]
(iii) is used to kill microbes in water treatment .................................................................... [1]
(iv) forms an amphoteric oxide ........................................................................................... [1]
(v) forms an oxide which causes acid rain ......................................................................... [1]
(vi) has an oxidation number of –1 when it forms a compound with hydrogen.
....................................................................................................................................... [1]
(b) The relative atomic masses of elements can be calculated from the relative masses of isotopes
and their percentage abundances.
(i) Identify the isotope to which all relative masses are compared.
....................................................................................................................................... [1]
(ii) Table 2.1 shows the relative masses and the percentage abundances of the two isotopes
in a sample of magnesium.
Table 2.1
relative mass of isotope percentage abundance of isotope
24 85
26 15
Calculate the relative atomic mass of magnesium to one decimal place.
relative atomic mass = .............................. [2]
© UCLES 2023 0620/43/M/J/23
Cambridge IGCSE™
*9534637521*
CHEMISTRY 0620/43
Paper 4 Theory (Extended) May/June 2023
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.
IB23 06_0620_43/2RP
© UCLES 2023 [Turn over
, www.dynamicpapers.com
2
1 Some symbol equations and word equations, A to J, are shown.
A H+ + OH– → H2O
B Cr3+ + 3OH– → Cr(OH)3
C methane + chlorine → chloromethane + hydrogen chloride
D propene + bromine → 1,2-dibromopropane
E C10H22 → C8H18 + C2H4
F chlorine + aqueous potassium bromide → bromine + aqueous potassium chloride
G methane + oxygen → carbon monoxide + water
H C2H5COOH + CH3OH → C2H5COOCH3 + H2O
I hydrogen + oxygen → water
J 6CO2 + 6H2O → C6H12O6 + 6O2
Use the equations to answer the questions that follow.
Each equation may be used once, more than once, or not at all.
Give the letter, A to J, for the equation which represents:
(a) photosynthesis ..................................................................................................................... [1]
(b) an addition reaction ............................................................................................................. [1]
(c) a precipitation reaction ........................................................................................................ [1]
(d) incomplete combustion ........................................................................................................ [1]
(e) a displacement reaction ....................................................................................................... [1]
(f) a substitution reaction. ......................................................................................................... [1]
[Total: 6]
© UCLES 2023 0620/43/M/J/23
, www.dynamicpapers.com
3
Question 2 starts on the next page.
© UCLES 2023 0620/43/M/J/23 [Turn over
, www.dynamicpapers.com
4
2 (a) The symbols of the elements in Period 3 of the Periodic Table are shown.
Na Mg Al Si P S Cl Ar
Use the symbols of the elements in Period 3 to answer the questions that follow.
Each symbol may be used once, more than once, or not at all.
Give the symbol of the element that:
(i) is present in purified bauxite ......................................................................................... [1]
(ii) contains atoms with a full outer shell of electrons ........................................................ [1]
(iii) is used to kill microbes in water treatment .................................................................... [1]
(iv) forms an amphoteric oxide ........................................................................................... [1]
(v) forms an oxide which causes acid rain ......................................................................... [1]
(vi) has an oxidation number of –1 when it forms a compound with hydrogen.
....................................................................................................................................... [1]
(b) The relative atomic masses of elements can be calculated from the relative masses of isotopes
and their percentage abundances.
(i) Identify the isotope to which all relative masses are compared.
....................................................................................................................................... [1]
(ii) Table 2.1 shows the relative masses and the percentage abundances of the two isotopes
in a sample of magnesium.
Table 2.1
relative mass of isotope percentage abundance of isotope
24 85
26 15
Calculate the relative atomic mass of magnesium to one decimal place.
relative atomic mass = .............................. [2]
© UCLES 2023 0620/43/M/J/23
