2018 Sec 4 Pure Chemistry SA2 Geylang Methodist School

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Geylang Methodist School (Secondary)
Preliminary Examination 2018
CHEMISTRY 6092/01
Paper 1 Multiple Choice Sec 4 Express
Additional materials : OAS 1 hour
Setter : Mrs Loh Kim Woon 20 August 2018
READ THESE INSTRUCTIONS FIRST
Write in soft pencil.

Do not use staples, paper clips, highlighters, glue or correction fluid.
Write your name, class and register number on the Answer Sheet in the spaces
provided unless this has been done for you.
There are forty questions on this paper. Answer all questions.

For each question there are four possible answers A, B, C and D.
Choose the one you consider correct and record your choice in soft pencil on the
separate Answer Sheet.
Read the instructions on the Answer Sheet very carefully.
Each correct answer will score one mark.

A mark will not be deducted for a wrong answer.
Any rough working should be done in this booklet.
A copy of the Periodic Table is printed on page 16.
This document consists of 16 printed pages.
[Turn over
2 GMS(S)/Chem/P1/Prelim2018/4E
1 Which of the following pairs of substances can be separated by heating?
A ammonium chloride and potassium iodide

B copper (II) nitrate and potassium iodide
C ammonium chloride and iodine
D sodium chloride and copper (II) nitrate
2 The table shows the colours and the solubilities in water of four solids.
solid colour solubility in water

W blue insoluble
X blue soluble
Y white insoluble
Z white soluble
A mixture containing two of the solids is added to excess water, stirred and filtered.
A blue filtrate and a white residue are obtained.
Which two solids are present in the mixture?
A W and X B W and Y
C X and Y D X and Z
3 An experiment is carried out to investigate the rate of reaction when calcium carbonate
reacts with hydrochloric acid.
The volume of carbon dioxide gas given off is measured at different intervals of time.
The diagram shows pieces of apparatus used to collect gases.
1 2 3
downward delivery calibrated gas syringe displacement of water
with a graduated tube
Which apparatus is suitable to collect and measure the volume of the carbon dioxide?
A 1 only B 3 only C 2 and 3 D 1, 2 and 3
4 Solution X contains two anions. Tests are carried out as shown in the diagram below.
barium
nitrate
nitric acid solution
colourless solution
is added is added
solution X and effervescence no change
of gas
silver nitrate
is added
white precipitate
What anions are found in solution X?
A sulfate ions and carbonate ions

B carbonate ions and chloride ions
C sulfate ions and chloride ions
D nitrate ions and carbonate ions
5 Which statement correctly explains why chlorine, Cl2, at 40°C diffuses more slowly than
neon, Ne, at 20°C?
A Chlorine has a relative molecular mass of 71 whilst neon has a relative atomic
mass of 20.
B Chlorine is at a higher temperature than neon.
C Chlorine is diatomic and neon is monatomic.
D Chlorine is more reactive than neon.
6 Four statements are being made about elements, compounds and mixtures by a
student.
Statement 1: Elements and compounds have fixed melting points.
Statement 2: The properties of a compound are similar to that of its elements.
Statement 3: A mixture can be separated into its components by physical means.
Statement 4: Elements can exist either in the form of atoms or molecules.
How many of the above statement(s) is/are not correct?
A one
B two
C three
D four
7 Deuterium, D, is an isotope of hydrogen.

Which statement about deuterium is not correct?
A It reacts with ethene, C2H4, to form a compound CH2DCH2D.

B An atom of deuterium contains one proton.
C It has the same density as hydrogen.
D It forms the ion D+.
8 A molecule of sulfuric acid has the structural formula shown.
How many electrons are involved in forming all the covalent bonds in one molecule of
sulfuric acid?
A 6 B 8 C 12 D 16
9 An investigation of the properties of the chlorides of Period III elements shows that the
boiling points of sodium chloride and silicon tetrachloride are 1465 oC and 57oC
respectively. This difference in boiling points is a result of
A covalent bonds being weaker than ionic bonds.

B sodium chloride having strong metallic bonds.
C silicon tetrachloride having weak intermolecular forces of attraction.
D silicon forming weaker bonds with chlorine than does sodium.
10 Compound P is the only substance formed when two volumes of ammonia gas react with
one volume of carbon dioxide gas (both volumes being measured at r.t.p.).
What is the formula of P?
A NH2CO2NH4
B (NH2)2CO
C NH4CO2NH4
D (NH4)2CO3
11 When sugar (Mr = 342) is fermented using yeast, the following reaction takes
place.
C12H22O11 + H2O o 4C2H5OH + 4CO2
What volume of carbon dioxide, at r.t.p., would be produced by the complete

fermentation of 1 kg of sugar?
A 342 x 4 x 24 dm3 B 1000 x 24 dm3

1000 342 x 4
C 342 x 24 dm3 D 1000 x 4 x 24 dm3

1000 x 4 342
12 On collision, airbags in cars inflate rapidly due to the production of nitrogen.

The nitrogen is formed, in two consecutive steps, according to the following equations.
Step 1: 2NaN3 → 2Na + 3N2
Step 2: 10Na + 2KNO3 → K2O + 5Na2O + N2
What is the total number of moles of nitrogen gas that can be produced from one mole
of sodium azide, NaN3?
A 1.5 B 1.6 C 3.2 D 4.0

13 Which property would all the hydrogen compounds of the Group VII elements possess?
A They form covalent compounds.

B They are solids at room temperature.
C They form alkaline aqueous solutions.
D They conduct electricity when molten.
14 The properties of the oxides of four elements K, L, M and N in the third period of the
Periodic Table are given below.
x The oxide of K is insoluble in water and dilute acid but soluble in concentrated alkali.
x The oxide of L reacts with both dilute acid and dilute alkali.
x The oxide of M reacts with dilute alkali at room temperature.
x The oxide of N dissolves in water to form an alkaline solution.
If K, L, M and N are placed in order of increasing atomic number, which order is correct?
A K, L, M, N
B N, M, K, L
C N, L, K, M
D L, K, N, M
15 A coil of clean copper wire is suspended in aqueous silver nitrate. Crystals of silver are
deposited on the copper wire.
Which statement is not correct?
A The copper is oxidised.

B The total mass of the crystals of silver increases gradually.
C The total number of positive ions in the solution is unchanged.
D The solution turns blue.
16 Which statement about the production of iron from iron oxide in a blast furnace is correct?
A Limestone is used to remove basic impurities.

B The reaction between the iron oxide and carbon monoxide liberates carbon dioxide.
C The iron is obtained using carbon monoxide as an oxidising agent.
D The iron oxide is reduced by carbon dioxide.
17 A known mass of potassium carbonate was placed in an open crucible and heated until
there was no further change observed.
Which graph shows the change in mass of the crucible and its contents?
A B
mass / g mass / g
time / s time / s
C D
mass / g mass / g
time / s time / s
18 A sample of three gases was passed through the apparatus shown below. It was found
that only one gas was collected in the gas jar at the end.
Which of the following could be the mixture of gases in the sample?
A ammonia, hydrogen, carbon monoxide

B ammonia, sulfur dioxide, carbon monoxide
C nitrogen, helium, carbon dioxide
D oxygen, nitrogen, hydrogen chloride
19 Nitrogenous fertiliser such as ammonium nitrate is used to increase crop yield.
Which substance can be added to increase the pH of acidic soil containing ammonium
nitrate without causing a loss of nitrogen?
A calcium carbonate
B calcium hydroxide
C magnesium hydroxide
D potassium hydroxide
20 Which of the following does not show the appropriate reagents used for preparation of
the named salts?
salt reagents
A barium sulfate barium nitrate and sulfuric acid
B lead(II) chloride lead(II) nitrate and hydrochloric acid
C lithium nitrate lithium hydroxide and nitric acid
D magnesium chloride magnesium sulfate and hydrochloric acid
21 Which of the following is true about the Haber Process?
A The catalyst in the reaction is iron(III) oxide.

B The optimum temperature for the reaction is 450qC.
C A pressure of above 600 atm will result in lower yields.
D 1 mole of nitrogen reacts with 3 moles of hydrogen to form 2 moles of ammonia.
22 Which of the following statements best describes the mechanism of a hydrogen-oxygen

fuel cell?
A Hydrogen and oxygen undergo redox reaction to generate electricity.

B Hydrogen ions react with hydroxide ions to generate electricity.
C Electricity is used to provide heat energy.
D Electricity is used to generate hydrogen and oxygen.
23 The energy profile diagram for the forward direction of a reversible reaction is shown.
activation energy
energy
∆H
progress of reaction
For the reverse reaction, which row correctly shows the sign of the activation energy
and the type of enthalpy change?
sign of activation energy type of enthalpy change

A negative endothermic
B negative exothermic
C positive endothermic
D positive exothermic
24 In four separate experiments, 1, 2, 3 and 4, nitric acid was added to excess marble chips
and the volume of carbon dioxide formed was measured.
In all four experiments the same volume of nitric acid was used.
Its concentration, or temperature, or both concentration and temperature, were changed.
The results of the experiments are shown on the graph.
Which statement is correct?
A A lower concentration of acid was used in experiment 3 than in experiment 1.

B Experiment 4 was faster than experiment 3.
C The acid used in experiment 2 was of a lower concentration than in experiment 1.
D The temperature of the acid was the same in experiments 1 and 2.
25 The following changes could be made to the conditions in the reaction between zinc and
hydrochloric acid.
1 increase in concentration of the acid

2 increase in particle size of the zinc
3 increase in pressure on the system
4 increase in temperature of the system
Which pair of changes will increase the rate of reaction?
A 1 and 2 B 1 and 4
C 2 and 3 D 3 and 4
26 Disproportionation is a reaction in which the same element is both oxidised and reduced.
Which reaction is an example of disproportionation?
A 3Cu + 8HNO3 o 3Cu(NO3)2 + 2NO + 4H2O

B 2KOH + H2SO4 o K2SO4 + 2H2O
C 2NO2 + H2O o HNO3 + HNO2
D 2Pb(NO3)2 o 2PbO + 4NO2 + O2
27 Aqueous potassium iodide, KI(aq), can be used as a test reagent in redox reactions.
Iodide ions are readily ……X…… A positive result for the test is when the solution
changes colour from ……Y…… to ……Z……..
Which words correctly complete gaps X, Y and Z?
X Y Z
A oxidised brown colourless
B oxidised colourless brown
C reduced brown colourless
D reduced colourless brown
28 In an electrolysis experiment, the same amount of charge deposited 54.0 g of silver and
8.5 g of vanadium.
What is the charge on the vanadium ion?
A 1+
B 2+
C 3+
D 4+
29 With reference to the diagram below, which of the following statements is correct?
electron flow
copper electrode made of metal X

l t d
dilute sulfuric acid
A Copper electrode is the negative electrode.

B Metal X is below copper in the reactivity series.
C The mass of the copper electrode decreases.
D The mass of the metal X electrode decreases.
30 When electrolysed using inert electrodes, which dilute solution would produce the
greatest increase in mass of the cathode?
inert
electrode
A B C D
aluminium copper(II) lead silver
sulfate sulfate nitrate nitrate
31 The table shows some atmospheric pollutants and their possible effects.
Which row is not correct?
pollutant effect
A CFCs cause depletion of the ozone
B CO2 layer forms photochemical smog
C CO is poisonous to humans
D NO2 forms acid rain
32 The diagram below represents a section of a catalytic converter on the exhaust system
of a car. Harmful gases are converted into carbon dioxide, nitrogen and water vapour.
CO CO2
hydrocarbons N2
NOx H2O
platinum and rhodium catalyst
Which processes take place in this catalytic converter?

I Carbon monoxide and hydrocarbons react together.
II Carbon monoxide and nitrogen oxides react together.
III Platinum and rhodium catalyse redox reactions.
A I, II and III
B I and II only
C II and III only
D I and III only
33 Which statement(s) best explains why bitumen has a higher boiling point than paraffin?
1 Bitumen is more reactive than paraffin.

2 Bitumen is a pure substance whereas paraffin is a mixture.
3 Forces of attraction between the molecules of paraffin are weaker than that
between the molecules of bitumen.
4 There are smaller molecules in bitumen compared to the molecules in paraffin.
A 1 and 2 B 1, 2 and 3
C 3 only D 3 and 4
34 Which compound is the most viscous and the least flammable?
A C6H14 B C8H18
C C10H22 D C12H26
35 The second member of a homologous series has the formula C 7H8.
What is the formula of the first member?
A C6H6 B C6H8
C C6H7 D C7H6
36 An ester is produced by reacting together the carboxylic acid HCO2H and the alcohol
CH3CH2CH2OH.
What is the name and structure of this ester?
name structure
A methyl propanoate CH3CH2CO2CH3
B methyl propanoate HCO2CH2CH2CH3
C propyl methanoate CH3CH2CO2CH3
D propyl methanoate HCO2CH2CH2CH3
37 Compound Y
x has the empirical formula CH2,

x has an Mr of 56,
x forms two alcohols that have different structural formulae when reacted with
steam.
What is compound Y?
A B
C D
38 The structure of a polymer is shown below.
CH CH2 CH CH2 CH CH2
CH2 CH3 CH2 CH3 CH2 CH3
What is the molecular formula of the monomer?
A C2H4
B C3H8
C C4H8
D C4H10
39 Aspirin is a drug which is used as a general pain killer. The structural formula of aspirin
is shown below.
Which of the following statements about aspirin is false?

A Its aqueous solution reacts with sodium carbonate.
B It decolourised aqueous bromine.
C It is formed from an alcohol and a carboxylic acid.
D It turns purple acidified aqueous potassium manganate (VII) colourless.
40 The diagrams show four monomers.
How many of these monomers would react with the molecule below to form a polymer?
A 1
B 2
C 3
D 4
End of Paper
Preliminary Examination 2018
Candidate
Name
Class Index Number

___________________________________________________________
CHEMISTRY 6092/02
Paper 2 Sec 4 Express
Additional materials : Writing papers 1 hour 45 minutes
Setter : Ms Tan Lay Ming 17 August 2018
READ THESE INSTRUCTIONS FIRST
Write your name, index number and class on all the work you hand in.
Write in dark blue or black pen on both sides of the paper.
Do not use staples, paper clips, highlighters, glue or correction fluid.
Section A
Answer all questions in the spaces provided.
Section B
Answer all three questions, the last question is in the form either/or.
Write your answers in the writing papers provided.
At the end of the examination, hand in Section A and Section B separately.

The number of marks is given in brackets [ ] at the end of each question or part
question.
A copy of the Periodic Table is printed on page 19.

For Examiner’s Use
Section A /50
B8 /12
B9 / 8
B10 /10
Total
80
This document consists of 19 printed pages and 1 blank page.
[Turn over
2 GMS(S)/CHEM/P2/PRELIM2018/4E
Section A
Answer all questions in this section in the spaces provided.
The total mark for this section is 50.
A1 The following table shows some substances and their properties.
substance melting boiling solubility in electrical conductivity

point (oC) point (oC) water
when solid when liquid
A 3550 4830 insoluble poor poor
B -55.6 -78.5 slightly poor poor
soluble
C 1085 2562 insoluble good good
D 801 1413 soluble poor good
E -38.8 357 insoluble good good
(a) Using the letters A, B, C, D and E, which substance(s) is/are likely to have a
(i) simple molecular structure, …………………………………………….… [1]
(ii) giant covalent structure, ………………………………………………. [1]
(iii) giant metallic structure. ………………………………………………. [1]
(b) Suggest a possible identity for element E.
…………………………………………………………………………………....... [1]
(c) A student passed a current through molten substance D and after a while, a
gas which rekindled a glowing splint was produced at the anode.
Write an ionic half-equation, including state symbols, for the reaction that
happened at the anode.
…………………………………………………………………………………........ [2]
[Total: 6]
A2 The bond dissociation energies of some hydrogen halides are shown in the chart
below. Bond dissociation energy is the energy that must be provided to the molecule
in order to break the bond.
(a) Describe the trend shown in the above chart.
…..……………………………………………………………………………………. [1]
(b) Predict the bond dissociation energy of hydrogen astatide, HAt, by drawing the
rectangular bar in the chart above. [1]
(c) (i) Suggest which one of the hydrogen halides forms the strongest acid.
………………………………………………………………………………….. [1]
(ii) Explain your answer to (c)(i).
………………………………………………………………………………………
……………………………………………………………………………….…. [2]
(d) Hydrogen bromide can be produced by reacting hydrogen and bromine

according to the following reaction.
H2 (g) + Br2 (g) Æ 2HBr (g)
The bond energies of some bonds are shown in the table below.
bond H-H H-Br Br-Br

bond energy (kJ/mol) 432 363 193
Calculate the enthalpy change of this reaction and state whether it is

exothermic or endothermic.
[2]
[Total: 7]
A3 This information comes from a textbook about elderberries.
Elderberries are widely used in wine making. Extract of

elderberries is a useful pH indicator and it can be
separated by chromatography.
As an indicator, the colour of the extract changes to pink

at a pH of 2 – 3 and to blue at a pH of 11 – 12.
elderberries
(a) The chromatogram shown below was obtained when water was added to a drop
of elderberries extract at the centre of a filter paper.
(i) Predict the colour of the elderberries extract at pH 7.
…………………………………………………………………………………[1]
(ii) An alternative set-up for the above experiment was shown below.
dye Rf value distance stopper

travelled (cm) solvent front
filter paper strip
light blue 0.2
boiling tube
dark pink 0.4 1.00
position of extract at the
start of the experiment
dark blue 0.5
water
Given that the distance travelled by the dark pink dye is 1.00 cm,
complete the table above by stating the distance travelled by the light
blue and dark blue dyes. [2]
(b) The diagram below shows how pH values changed during a titration when an
acid was added from a burette into a solution of an alkali. Some drops of
elderberries extract were added at the start of titration.
pH
5 10 15 20 25 30 35 40
Volume of acid added (cm3)
(i) Suggest one possible chemical formula of the alkali.
………………………………………………………………………………... [1]
(ii) State the colour of the elderberries extract when the volume of acid
added was
20 cm3 , ……………………… [1]
30 cm3 . ……………………… [1]
[Total: 6]
A4 Most vehicles have petrol or diesel engines, but some use fuel cells.
The flow charts show the substances entering and leaving a petrol engine and a fuel
cell.
(a) Complete the flow chart for the fuel cell by filling in the empty boxes. [1]
(b) The waste products from vehicles with petrol engines cause more harm to
human health than those from vehicles with fuel cells.
Explain why this statement is true.
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………..……. [3]
(c) Hydrogen for fuel cells can be obtained from water by electrolysis.
Electricity is used to provide energy for the electrolysis.
Complete the energy profile diagram for the electrolysis of water.
Your diagram should include

x the formulae of the products of the electrolysis,
x a label for the enthalpy change of reaction.
energy
____H2O____
progress of reaction [2]
[Total: 6]
A5 A laboratory assistant has six elements that are consecutively arranged in the
Periodic Table. He randomly assigns each element a letter, T, V, W, X, Y and Z. The
letters do not represent the atomic symbols and the order of the elements.
He carried out some experiments on the elements and found the following properties.
x V2 reacts with X2 to form a compound VX3.
x Y forms a carbonate that decomposes to carbon dioxide and an oxide on
heating.
x W reacts with T2 to form W 2T. W 2T dissolves in water to form a solution that
turns purple with addition of Universal Indicator.
x Z is a gaseous element. It is used in advertising strip lights.
(a) Identify the following elements
(i) T, ………………………………………… [1]
(ii) W, ………………………………………… [1]
(iii) Z. ………………………………………… [1]
(b) Write down the product(s) formed from the reaction between
(i) Y and Cl2, ………………………………………………………………… [1]
(ii) X2 and NaCl. ……………………………………………………………….... [1]
(c) State the industrial conditions required to produce VH3. (H is hydrogen).
………………………………………………..…...………….……………….……………
………………………………………………...………………………………….….… [2]
[Total: 7]
A6 The table below shows some information regarding three materials. They are Kevlar,
polyglycine and Teflon.
name of material structure of polymer
Kevlar
polyglycine
Teflon
(a) Identify the reaction that formed
(i) Kevlar, ………………………………………………… [1]
(ii) polyglycine, ………………………………………………… [1]
(iii) Teflon. ………………………………………………… [1]
(b) During polymerisation to form Kevlar and polyglycine, hydrogen chloride and
water are released respectively.
Draw the structure of the monomer(s) that formed
(i) Kevlar,
[2]
(ii) polyglycine.
[1]
(c) Suggest the structural formulae of the products formed from a reaction between
glycine and ethanol.
[2]
[Total: 8]
A7 A new type of electroplating is known as ‘brush electroplating’.

It is used to electroplate zinc onto very large iron supports to be used in buildings.
The iron supports are too big to be plated in a normal electrolysis tank.
During the process, a metal brush spreads a layer of aqueous zinc sulfate over the
iron surface.
A battery gives the brush a positive charge and gives the iron support a negative
charge.
A layer of zinc forms on the surface of the iron support.
layerofofaqueous
layer zinc sulfate
zinc sulfate
(a) The surface of the iron acts as a cathode.

Zinc ions from the solution form zinc on the surface of the iron.
Write an ionic half-equation, with state symbols, for this reaction.
………………………………………………………………………………………… [2]
(b) Two different designs of metal brush are available.

One type of brush is made from zinc, one type is made from platinum.
As the electrolysis takes place, each brush has a different effect on the
concentration of zinc ions in the solution.
(i) What will happen to the concentration of the zinc ions during the
electrolysis if the brush is made from platinum?
………………………………………………………………………………… [1]
(ii) What will happen to the concentration of the zinc ions during the
electrolysis if the brush is made from zinc?
………………………………………………………………………………... [1]
(iii) Platinum brushes are much more expensive than zinc brushes.
However, zinc brushes need replacing regularly but platinum brushes do
not.
Explain why.
…………………………………………………………………………………….
……………………………………………………………………………..…. [2]
(c) During the process, a worker needs to hold the brush.
Which of the following materials would be a good choice for the handle of the
brush? Give a reason for your answer.
chromium copper graphite iron poly(ethene)
material ……………………………………………………………………………… [1]
reason ……………………………………………………………………………….. [1]
(d) Explain why iron supports coated with zinc do not rust, even if the zinc coating
is damaged.
…………………………………………………………………………………………….
………………………………………………………………………………………... [2]
[Total: 10]
End of Section A
Section B
Answer all three questions from this section.
The last question is in the form of an either/or and only one of the alternatives should be
attempted.
The total mark for this section is 30.
Write your answers in the writing papers provided.
B8 Chlorofluorocarbons (CFCs) are inert on the Earth’s surface. However in the

stratosphere, they are very reactive. CFCs are part of a group of compounds which
can be classfied as ozone depleting compounds. Other than CFCs, there are also
hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs) and perfluorocarbons
(PFCs). Some common examples of CFC and HCFC molecules are shown below with
their names.
A naming system for these substances was devised several decades ago. The
prefixes to the name tell us the elements present in the compound as shown in the
table below.
prefix elements present

PFC carbon, fluorine
CFC carbon, fluorine, chlorine
HFC hydrogen, carbon, fluorine
HCFC hydrogen, carbon, fluorine, chlorine
The numbers suffixed to the names of the compounds give us the number of each
type of atom present in one molecule of the compound. The key to decoding the
number is simply to add 90 to the number suffixed to the name.
.
For example, to decode the number of atoms in CFC-113a, we add 113 to 90 to obtain
203. The first number, 2, tells us the number of carbon atoms, the second number, 0,
tells us the number of hydrogen atoms, and the third number, 3, tells us the number of
fluorine atoms. Chlorine atoms make up the remaining bonds since all these
compounds are saturated.
The letter ‘a’ in CFC-113a tells us about the structural formula of the compound. The
arrangement of the type of atoms in the compound that most evenly distributes atomic
masses has no letter. The second most even distribution is given the letter ‘a’, the third
most even distribution is given the letter ‘b’, so on and so forth.
molecule atomic mass on left carbon atomic mass on right carbon
73.5 90
57 106.5
Although most of these substances are harmful to the ozone layer, they can also be
used to make polymers by first converting them to alkenes. For example, HCFCs react
with potassium hydroxide which is dissolved in ethanol (solvent) to give an alkene,
potassium chloride and water. An example of the reaction is shown below.
+ KOH ethanol + H2O + KCl
The alkene produced from the above reaction can be used to make useful polymers
such as the one shown below.
(a) Draw the structure of a PFC molecule with two carbon atoms. [1]
(b) Copy the table below and draw the other two isomers of HCFC-141 in the
correct respective boxes. [2]
HCFC-141a HCFC-141b
(c) A student comments that HFCs are safer alternatives to CFCs as HFCs do not
harm the environment like CFCs do.
Explain why the student is correct. [1]
(d) Use the naming system discussed in the passage, write down the names of the
following molecules.
(i)
[1]
(ii)
[2]
(e) (i) A scientist wants to produce the polymer, polyvinyl fluoride, using
HCFCs.
polyvinyl fluoride
Using a suitable HCFC, write down two equations showing the reactions
he has to carry out to produce polyvinyl fluoride. Show the structures of
all the organic compounds in your equations. [3]
(ii) Samples of the polyvinyl fluoride polymer produced were analysed and
found to have a maximum relative molecular mass of 12000.
What is the maximum number of repeating units for this polymer? [2]
[Total: 12]
B9 Fats and oils such as butter, lard, tallow and coconut are compounds formed by the
reaction between fatty acids and an alcohol. Fatty acids may be saturated or
unsaturated in nature.
A student collected some data about fatty acids present in some common types of oil
or fats, which are shown in the table below.
% by mass of fatty acid present in substance

types lauric palmic stearic oleic acid linoleic
of fatty acid acid acid acid
types of acids
oil or fats
butter
b tt 2-3 23-26 10-13 30-40 4-5
lard <1 28-30 12-18 41-48 6-7
tallow <1 24-32 14-32 35-38 2-4
coconut 45-51 4-10 1-5 2-10 0-2
Lauric acid, palmic acid and linoleic acid are unsaturated fatty acids while stearic acid
and oleic acid are saturated fatty acids. Fats and oils containing saturated fatty acids
are less healthy than unsaturated ones.
(a) Linoleic acid, C17H31COOH is a fatty acid found mainly in sunflower or palm oil.
Stearic acid has a molecular formula of C17H35COOH.
(i) State the reagent and conditions required to form stearic acid from
linoleic acid in the laboratory. [2]
(ii) Describe an experiment to show that all the linoleic acid had reacted
completely to produce stearic acid. You are to include the expected
observation. [3]
(b) Which types of oil or fats is the healthiest? Explain your answer. [1]
(c) 10 g of oil (Mr = 800) completely reacted with 1.8 dm 3 of hydrogen measured at
room temperature and pressure.
Calculate the number of moles of hydrogen that react with one mole of the oil.
Hence, deduce how many C = C bonds there are in one molecule of this oil. [2]
[Total: 8]
EITHER
B10 Sulfur dioxide reacts with chlorine gas in the presence of a catalyst to form a single
liquid product, sulfuryl chloride, SO2Cl2.
(a) Draw a ‘dot-and-cross’ diagram for chlorine gas.

Show the outer shell electrons only. [2]
(b) Student A says, “The sulfur in sulfur dioxide is oxidised.”

Student B says, “Sulfur dioxide is an oxidising agent.”
Do you agree with both of them, one of them or neither of them?

Explain your answer. [2]
(c) Sulfuryl chloride can be heated to produce sulfur dioxide and chlorine.
How can the identities of these two gases be confirmed? [2]
(d) Sulfuryl chloride reacts with water to form two strong acids. One is a dibasic
acid while the other is a monobasic acid.
(i) Write down the equation for this reaction. [1]
(ii) Calculate the volume of 0.5 mol/dm3 of dilute sodium hydroxide required
to completely neutralise the acidic solution produced by reacting one
mole of sulfuryl chloride with water. [3]
[Total: 10]
OR
B10 Calcium carbonate decomposes when it is heated.
CaCO3 (s) Æ CaO (s) + CO2 (g)
In an experiment, 10.5 g of calcium carbonate was heated to a constant temperature.
(a) Sketch a graph to show how the volume of carbon dioxide collected changes
with time.
(b) Calculate the maximum volume of carbon dioxide, at room temperature and
pressure, that can be formed from 10.5 g of calcium carbonate. [2]
(c) The experiment was repeated under the same conditions using zinc carbonate
instead of calcium carbonate.
(i) Describe how the rates of the reactions would be different.

(ii) The same mass (10.5 g) of zinc carbonate was used. Would the total
volume of carbon dioxide formed be the same?
[Total: 10]
End of paper
BLANK PAGE
Marking Scheme

Preliminary Exam 2018
Chemistry 6092
Paper 1
1 A 11 D 21 B 31 B
2 C 12 B 22 A 32 C
3 C 13 A 23 D 33 C
4 B 14 C 24 A 34 D
5 A 15 C 25 B 35
5 A
6 A 16 B 26 C 36 D
7 C 17 B 27 B 37
37 B
8 D 18 B 28 C 38
3 8 C
9 C 19 A 29 D 39
39 D
10 A 20 D 30 D 40 C
Paper 2
Section A
A1 (a) i. B [1]
ii. A [1]
iii. C and E [1]
Note: both
both a
answers
n we
ns ers m
must
ustt be
us b correct to award 1 mark.
(b) Mercury [1]

(c) O22-- ((l)
2O l) Æ O2 (g
(g)) + 4e Note: [1] for chemically balanced ionic [2]
equation without state symbols.
A2 (a) The bond dissociation energies of hydrogen halides decreases [1]

from HF to HAt.
1
A2 (b) [1]
Accept if answer is between 200-275kJ/mol

(c) i. HAt Note: chemical name is acceptable. [1]
ii. HAt has the lowest bond

nd dissociation
dis
isso
sociat
atio
ion
n en
ener
energy
ergy
g therefore [1]
hydrogen ions will be pr
prod
produced
oduc
u edd most
mos
ostt easily.
e sily.
ea [1]
(d) Enthalpy change = 432 + 193
193 – 2(
2(36
2(363)
363)
3) = -101 kJ [1]
Exothermic reaction [1]
A3 (a) i Purple
Pu
urp
rple
le / violet
vio
iole
et [1]
Acceptable:
Ac
cce
cept
ptab
able:: bluish-purple
blui
bl u sh-purple or purplish-blue
(a) ii Light bl
blue
u – 0.500 (3sf) [1]
Dark blue – 1.25 (3sf) [1]
(b) i Any strong alkali such as NaOH, KOH [1]
(b) ii 20 cm3 – blue [1]

30 cm3 - pink [1]
A4 (a) [1]
Note: Both answers
must be correct to
award 1 mark.
(b) Steam, which is the product of fuel cell, has no adverse effect on [1]
human health.
Waste product, like carbon monoxide, from incomplete combustion [1]
of petrol, can react with haemoglobin in blood to form [1]
carboxyhaemoglobin. As a result, haemoglobin cannot transport
oxygen to the rest of the body.
2
www.KiasuExamPaper.com
A4 (c) [2]
[1] – correc
correct
ct gr
grap
graph
aph
2H2 + O2 [1] – fo
for
or co
cor
correct
rrecct
labelling
labe
la belllling
2H2O
A5 (a) i. Oxygen [1]

ii. Sodium [1]
iii. Neon [1]
(b) i. YCl2 [1]

Accept:
Acceppt: magnesium
magn
ma g esiu
um chloride
chlo
ch loride
ii. Na
NaXX an
and
a d Cl2 [1]
Accept:
Accept
pt:: so
sodi
sodium
dium
um ffluoride
luoride and chlorine
200-250atm
200
20 0-25
250a
0atm
tm
A5 (c) [2]
400-500
40
00-50
5000oC
Iron catalyst
Note: 2 marks for 3 correct answers; 1 mark for 2 correct answers.
answers
A6 (a) i. condensation polymerisation [1]

ii. condensation polymerisation [1]
iii. addition polymerisation [1]
(b) i. [1]
[1]
ii. [1]
3
(c) [1] for
each
A7 (a) Zn2+ (aq) + 2e Æ Zn (s) [2]

(b) i. Concentration of zinc ions will decrease over time. [1]
ii. Concentration of zinc ions will remain constant throughout [1]

electrolysis.
iii. Zinc brush will form zinc ions during electrolysis and will be used
use
sed
d [1]
up whereas platinum is an inert electrode therefore no o change
cha
hang
n e in [[1]]
[1
mass.
(c) Material – poly(ethene) [1]
Reason – It does not conduct electricity. [1]
A7(d) Zinc is more reactive than iron and therefore provides

prrov
ovid
idees
s sacrificial
sacriffici
cial
cia [1]
protection by corroding in place of iron. [1]
Section B
B8 (a) [1]
(b) HCFC-141a
HCFC
HC C-14
141a
1a HCFC-141b [2]
[1] for each box.

box
(c) HFCs do not contain chlorine atoms which will deplete the ozone layer. [1]
(d) i. CFC-111 [1]

ii. HCFC-132a Note: 1 mark for 132, 1 mark for a [2]
i.
4
H F H F
B8(e)
H C C H C C
[2]
I: Cl H + KOH ethanol H H + H2O + KCl
1 mark for correct HCFC used; 1 mark for equation.
[1]
n
II:
(e) ii. Mr of repeating unit: 12 x 2 + 19 + 1 x 3 = 46 [1]

No. of repeating units: 12000/46 = 260 (round down) [1]
B9(a) i. Reagent: hydrogen gas [1]

[1]
Conditions: Nickel as catalyst, 200 oC [1]
ii. Add aqueous bromine to the reaction mix mixture.

xtu re.
ure [1]
If all the linoleic acid has reacted, the reddish-brown
reddish b ro
h-br wn colour
ow ur of
our
colo of [1]
bromine remains.
b own colourr of
If some linoleic acid is present, the reddish-brown
reddish-br of bromine
bromine [1]
decolourises rapidly.
B9(b) Coconut oil is the healthiest.

It contains the highest percentage
percen nta
tage off unsa
ge o unsaturated
rate
tura
satu d fatty acids/ It contains [1]
ted
the lowestt percentage of satu
saturated
ura
rate fatty
d fatt
ted acids.
ty ac
a ids.
id s
Note: Explanation must be correct

corr
co ect in order
r ec order to
rder to award mark.
(c) No. of moles off hy

hydrogen
gen rreacted
d og
hydr eact
ea ed = 1.8/24
cted [2]
= 0.075 mol
ol
mo
[1]
Number of mole
moles oilil = 1
es of o 10/800
0/800
= 0.0125 mol
Numberr o
off mo
moles
mole s of hydrogen : number of moles of oil
les
0.075 : 0.0125 [1]
6 : 1
There are 6 double bonds in one molecule of oil.
5
Either
B10(a) [2]
1 mark for correct bonding, 1 mark for correct num

number
mbe
ber of e
electrons
lectro
rons
ro
on
nss ffor
o
or
each element.
(b) [1]
Student A is correct as the oxidation
oxidatio
on state
s ate
st e of
of ssulfur
ullfu
u fur in
in ssulfur
ullffu
u ur dioxide
diox
di
iox
oxid
ide
de
increases from +4 to +6.
Student B is wrong as sulfurr di
d
dioxide
oxxide re
o reduces
edu
d cce
es the oxidat
oxidation
tio
on stat
state
te of
o [1]
chlorine from 0 to -1, hence
hence
he e sulfur
sulfur
su llff r dioxide
de
e is
is the reducing
ng
n gaagent.
gent.
(c) SO2, when bubbled through
thrrough
gh acidifed
gh acid
ac idifife
edd potassium
pot
otas
assium
um
m mangana
manganate(VII),
nate
na te(VII), will [1]
decolourise th
the
he purp
purple
ple
e ssolution.
olut
ol u io
onn..
A damp
mp blue
mp e litmus
litm
ttm
mus
u p paper
ap
ap
per
er wh
er when
heen
n placed
pla
ace
ed near
ne
ear
ar the
the
h heated liquid will turn [1]
red
d be
b
before
efo
ore
r being
bei
e ng gbbleached
le
eache
ache
ac hed byy Cl
Cl2.
(d) i. SO
O2Cl2 + 2H
H2O Æ H2SO
O4 + 2HCl
2 HC
2H Cll [1]
(d) ii.i No. of
of m
moles
oles
ess o
off H2S
SOO4 = 1 mole
mo
m ole [3]
No
No. of
No. of moles
mol
oles
e off HCl
HCl = 2 moles
HC m les
mo
H2SO
S 4 + 2NaO
2NaOH
aOH
aOOH ÆNa
ÆNNaa2SO4 + 2H2O (equation not needed)
No.
No
o. off m
moles
oles
oles o
off Na
N
NaOH
aOH needed to neutralise 1 mole of H2SO4 Refe
Refer to
= 2 moles
molle
mo es [1]
[1
[1 mark
marks
alloc
allocation
HCl + Na
N
NaOH
aOH
O ÆNaCl + H2O (equation not needed) on th
the
No. of moles of NaOH needed to neutralise 2 moles of HCl left.
= 2 moles [1]
Total moles of NaOH needed = 4 moles
Volume of NaOH needed = 4 ÷ 0.5 = 8 dm3 [1]
6
OR
B10(a) volume of CO2 [1] –
/ cm3 graph
[1] -
correct
labels
and units
time / s
Note:
There isn’t a need to indicate the reaction rate on the graph.
The initial rate of decomposition is the fastest therefore the gradient is [1]
the steepest. As the rate of decomposition slows down, the gradient
becomes less steep. Finally reaction stops when all calcium carbonate [1]
is used up and gradient is zero.
(b) No. of moles of CaCO3 = 10.5 / 100 = 0.105 mol [1]

Volume of CO2 = 0.105 x 24 = 2.52 dm3 [1]
(c) i. The rate of decomposition of zinc carbonate will be faster than the [1]
rate of decomposition of calcium carbonate.
Zinc carbonate is less thermally stable than calcium carbonate
therefore it decomposes more readily than calcium carbonate. [1]
Note: Ignore reference to metal reactivity, no mark will be awarded.
ii. No. no mark
Possible explanation:
[1]
No. of moles of ZnCO3 = 10.5 / 125 = 0.084 mol
Volume of CO2 = 0.084 x 24 = 2.02 dm3 [1]
OR
[1]
Since there are fewer moles of zinc carbonate therefore the volume [1]
of carbon dioxide collected will be lesser.
END OF PAPER

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Paper 1 Multiple Choice Sec 4 Express

Additional materials : OAS 1 hour

Setter : Mrs Loh Kim Woon 20 August 2018

READ THESE INSTRUCTIONS FIRST

Write in soft pencil.

There are forty questions on this paper. Answer all questions.

Read the instructions on the Answer Sheet very carefully.

Each correct answer will score one mark.

This document consists of 16 printed pages.

1 Which of the following pairs of substances can be separated by heating?

A ammonium chloride and potassium iodide

solid colour solubility in water

Which two solids are present in the mixture?

A 1 only B 3 only C 2 and 3 D 1, 2 and 3

What anions are found in solution X?

A sulfate ions and carbonate ions

How many of the above statement(s) is/are not correct?

7 Deuterium, D, is an isotope of hydrogen.

A It reacts with ethene, C2H4, to form a compound CH2DCH2D.

8 A molecule of sulfuric acid has the structural formula shown.

A covalent bonds being weaker than ionic bonds.

What is the formula of P?

What volume of carbon dioxide, at r.t.p., would be produced by the complete

A 342 x 4 x 24 dm3 B 1000 x 24 dm3

C 342 x 24 dm3 D 1000 x 4 x 24 dm3

12 On collision, airbags in cars inflate rapidly due to the production of nitrogen.

Step 1: 2NaN3 → 2Na + 3N2

Step 2: 10Na + 2KNO3 → K2O + 5Na2O + N2

A 1.5 B 1.6 C 3.2 D 4.0

A They form covalent compounds.

Which statement is not correct?

A The copper is oxidised.

A Limestone is used to remove basic impurities.

Which of the following could be the mixture of gases in the sample?

A ammonia, hydrogen, carbon monoxide

19 Nitrogenous fertiliser such as ammonium nitrate is used to increase crop yield.

21 Which of the following is true about the Haber Process?

A The catalyst in the reaction is iron(III) oxide.

22 Which of the following statements best describes the mechanism of a hydrogen-oxygen

A Hydrogen and oxygen undergo redox reaction to generate electricity.

sign of activation energy type of enthalpy change

Which statement is correct?

A A lower concentration of acid was used in experiment 3 than in experiment 1.

1 increase in concentration of the acid

Which pair of changes will increase the rate of reaction?

Which reaction is an example of disproportionation?

A 3Cu + 8HNO3 o 3Cu(NO3)2 + 2NO + 4H2O

Which words correctly complete gaps X, Y and Z?

What is the charge on the vanadium ion?

copper electrode made of metal X

dilute sulfuric acid

A Copper electrode is the negative electrode.

Which row is not correct?

platinum and rhodium catalyst

Which processes take place in this catalytic converter?

1 Bitumen is more reactive than paraffin.

34 Which compound is the most viscous and the least flammable?

35 The second member of a homologous series has the formula C 7H8.