Science SPM Answers
(b) Carbon handprint refers to 11. B 12. B 13. B 14. C 15. D source
the actions taken to reduce 16. B 17. C • Chemicals in pesticides
greenhouse gases. from agricultural places
Q2 To ensure that there are no negative Subjective Questions lands
impacts to the sustainability of nature. 1. (a) Biochemical oxygen demand • Dumping of sewage which
Q3 • Cradle-to-grave is a term used to (BOD) is the total amount is faeces from humans and
refer to the life cycle of a product of oxygen required by livestock into our water
from raw material to its disposal. microorganisms such as bacteria sources
Residue, rubbish or waste is and fungi to break down organic (ii) Air-pollution
produced. matter in water. • Release of emissions
• Cradle-to-cradle is a term used in (b) (i) Location of water sample and heat from industrial
the analysis of life cycles to explain (ii) Time taken for methylene factories. The emissions
about a material or product that has blue to decolourise contain carbon monoxide,
been recycled into a new product (c) (i) carbon dioxide, nitrogen
at the end of its lifespan. This oxide or sulphur dioxide.
ensures that no waste is produce A B C • Release of emissions
and nothing is wasted. ✓ and poisonous gases
from vehicles and heavy
(ii) Distilled water is not polluted. machinery
Checkpoint 3.2 Its oxygen concentration
Q1 (a) Air pollution is higher. Therefore, the (c) • Biochemical oxygen demand
(BOD) is the amount of
Source: vehicle emissions, factory methylene blue solution dissolved oxygen needed
emissions in the distilled water by decomposers such as
Water pollution decolourises the slowest. bacteria to decompose
Source: leeching of fertiliser from 2. (a) (i) Location of experiment organic substances in a water
agricultural land, waste disposal (ii) Dust particle content resource.
from factories (b) (i) Slide R contains the highest • Methylene blue solution is
Q2 Release of greenhouse gases amount of dust particle used to detect the presence of
Q3 Increase in temperature of water content whereas slide Q oxygen in the water.
causing the death of aquatic life. contains the lowest dust • If the concentration of oxygen
particle content.
Food chain is affected. (ii) Slide R is placed in the most in water is low, the time taken
Q4 BOD is the amount of dissolved polluted location whereas for the methylene blue solution
to decolourise will be fast,
oxygen in the water. If the amount slide Q is placed in the least indicating a high BOD value.
of oxygen is low, this means there is polluted location. • Good quality water has a low
water pollution.
(c) The higher the level of air value of BOD.
Q5 Increased human population leads pollution in the location, the (d) • The turtle population is
to more activities that produces more dust particle present. decreasing.
even more pollutants and releases 3. (a) • Turtles die from eating the
greenhouse gases. plastic bags that were thrown
(i) gas Sulphur dioxide / out by humans.
carbon dioxide /
Checkpoint 3.3 • Enforcing the law against
nitrogen dioxide dumping of plastics into
Q1 Carbon dioxide is the cause of global (ii) solid Dust/smoke waterways
warming which can cause a negative particulates • Recycling plastics
impact to the world’s natural balance. floating in • Burning plastics in the
Q2 (a) Hybrid cars can use one of two the air incinerator
choices: petrol or electricity. Its • Plastics can be disposed of
usage is environment friendly as without releasing too much
it releases a smaller amount of (b) Yes, it is possible. There is
greenhouse gases. nuclear power station releases pollutants and poisonous gas
Form
(b) A green building is a building that their heated water into the rivers.
focuses on building practices that (c) Chapter
5
are good for the environment, 4 Rate of Reaction
using green building materials, Methane Hydrogen Carbon
more efficient use of energy and gas gas dioxide gas Checkpoint 4.1
water and good management of
solid waste. ✓ ✓ Q1 • Burning of wood
Q3 Alternative energy that is cleaner, (d) The melting of the polar ice caps • Firework explosion
carbon free, and can replace the / Flood / Climate change • Neutralisation
usage of fossil fuels 4. (a) Environmental pollution refers • Precipitation reaction
Q4 Fossil fuels release gases that pollute to the increase in quantities of (Any two)
the environment pollutants in nature due to the Q2 Rate of reaction is the measurement
actions of irresponsible people. of changes of quantity of reactant per
SPM Practice 3 (b) (i) Water pollution unit time or changes of quantity of
• The dumping of rubbish product per unit time.
Objective Questions such as plastic, food waste Q3 • Measuring mass of reactant or
1. B 2. D 3. A 4. D 5. D and solid wastes into rivers product
6. B 7. B 8. B 9. A 10. D which are our main water • Measuring changes in temperature
406
06 Ans Focus SC SPM.indd 406 24/02/2023 3:33 PM
Science SPM Answers
Q4 Rate of reaction (b) Hydrogen gas Checkpoint 5.2
Total hydrogen gas released (c) 0.40 – 0.50 cm s –1
3
= Q1 Hydrocarbon is a compound that
3
3 Time taken (d) 0.34 cm s –1 consists of carbon and hydrogen only.
= 50 cm 2. (a) Temperature Q2 Natural gas, petroleum, coal (Any
120 s (b) Rate of reaction in Experiment I
= 0.417 cm s –1 is higher than rate of reaction in two)
3
Experiment II. Q3 • Fractional distillation is a process
Q5 Rate of reaction (c) Experiment I of separating petroleum to a few
Total zinc powder reacted fractions which have properties and
= (d) • Adding catalyst – presence of use of their own.
Time taken catalyst increase the rate of • Petroleum can be separated to
= 0.65 g reaction its fraction components through
10 s • Breaking zinc granule into
= 0.065 g s –1 powder – Total surface area fractional distillation because each
fraction has its own boiling point.
of zinc exposed to reaction
Checkpoint 4.2 increases, hence rate of Q4 Saturated hydrocarbon: Ethane
Q1 Temperature, concentration of reaction also increase Unsaturated hydrocarbon: Ethene
reactant, size of reactant, presence of 3. (a) J : Sulphur dioxide Q5 • Solar
catalyst (b) K : Sulphuric acid • Hydroelectric
Q2 Temperature (c) Catalyst L: Vanadium(V) oxide • Biomass
Q3 Catalyst is a substance that can (d) Catalyst is used to increase rate
alter the rate of a reaction but does of reaction so that sulphuric acid Checkpoint 5.3
not change chemically at the end of can be produce faster. Q1 Carbon, hydrogen and oxygen
the reaction. With the presence of (e) No, reaction does not occur.
catalyst, reaction will becomes faster This is because the reaction of Q2 Methanol, ethanol (or any suitable
or slower. answer)
catalyst is specific.
Checkpoint 4.3 Q3 Yeast is added into sugar solution
and left at a place with warm
Q1 • Keep food in the refrigerator Chapter temperature for a few days in an
• Cook solid food in different sizes 5 Carbon Compounds air-sealed container. Yeast produces
• Cooking food in pressure cooker enzyme (zymase) to convert sugar to
Q2 • Contact Process for production of ethanol and carbon dioxide.
sulphuric acid Checkpoint 5.1
• Haber Process for production of Q1 (a) Carbon compounds are Q4 Alcohol is miscible in water in
ammonia compounds that consist of the any ratios. Ethanol is used in the
Q3 If temperature decrease, percentage element carbon with one type production of alcoholic drinks with
of ammonia production is higher. or more other elements such as different percentage content of
However, if lower temperature is use, hydrogen, oxygen and nitrogen. ethanol.
rate of reaction decreases. (b) Organic compounds are carbon Q5 Excessive and frequent consumption
Q4 Contact Process: Vanadium(V) oxide compounds obtained from living of alcoholic beverages can cause
catalyst things. liver cirrhosis. (or any suitable
Haber Process: Iron catalyst (c) Inorganic compounds are answer)
The usage of catalyst is to increase compounds that do not originate
from living things.
the rate of reaction so that ammonia Checkpoint 5.4
and sulphuric acid can be produced Q2 (a) Q1 • Palm oil – from oil palm fruit
faster. • Butter – from cow’s milk
Organic Inorganic (or any suitable answer)
SPM Practice 4 compounds compounds Q2 Carbon, hydrogen and oxygen Form
Objective Questions Obtained from Exist naturally in Q3 (a) Saturated fat
1. B 2. C 3. C 4. A 5. C living things air, water and soil (b) Saturated fats have high melting
6. C 7. C 8. D 9. B 10. A points and form solids at room 5
11. D 12. A 13. C 14. B Does not Some of the temperature.
contain compounds (c) Increase blood cholesterol level
Subjective Questions metallic contain metallic Checkpoint 5.5
1. (a) element element
3
Volume of gas (cm ) Q1 (a) K – Mesocarp / Pulp
70 (b) • Organic compounds: Alcohol, L – Shell
M – Kernel
60 sugar, coal, fats, petrol and
(g) natural gas (b) K and M
50 Q2 (a) Sterilisation
• Inorganic compounds: Carbon
40 dioxide, zinc carbonate, (b) Kill bacteria and soften fruit
30 calcium carbonate (c) Oil is extracted at a high pressure
Q3 • Provide carbon dioxide for the Q3 (a) Palm oil is used to produce
20 process of photosynthesis of plants. cooking oil, margarine, soap and
candle (Any two)
10 Time • Maintain balance of the carbon (b) Vitamin E and vitamin A
compounds on Earth.
0 (s)
30 60 90 120 150 180 210
407
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Science SPM Answers
Q4 Boil oil with an alkaline solution, then (d) • Copper dissolves to form copper(II)
add a little distilled water and stir until Hydrophilic ions which are positively-charged.
the mixture is well combined. After head • Copper(II) ions are attracted to the
that, add a little salt and filter the iron spoon cathode. Copper(II) ions
mixture. receive electron and form copper
atom which deposited on the iron
Hydrophobic tail
SPM Practice 5 spoon.
Chapter
Objective Questions 6 Electrochemistry Checkpoint 6.2
1. B 2. D 3. D 4. C 5. B Q1 Chemical energy → Electric energy
6. D 7. B 8. B 9. C 10. D Checkpoint 6.1 Q2 (a)
11. A 12. D 13. B 14. A 15. C Q1 (a) Electrolysis is the decomposition Switch
16. D 17. B 18. C 19. A 20. B process of an electrolyte using
21. C 22. A 23. D 24. B 25. C electric current. G Galvanometer
26. A 27. D 28. C 29. A 30. D (b) (i)
Subjective Questions Aluminium Copper strip
1. (a) The limewater turns cloudy. G strip
Carbon dioxide is released.
(b) Fermentation Anode Cathode Beaker Copper(II)
Yeast sulphate
(c) Glucose ⎯⎯→ Ethanol + solution
Carbon dioxide
(d) Through distillation (b) Positive terminal – Copper strip
2. (a) Ethanol burns with blue flame. Negative terminal – Aluminium
strip
(b) None (ii) Electrolyte: Copper(II) (c) As an electrolyte
chloride solution
(c) Ethanol + Oxygen → Carbon
dioxide + Water Anion: Chloride ion and Q3
hydroxide ion
(d) (i) Yes
(ii) Combustion of ethanol Cation: Copper(II) ion and Simple chemical Electrolytic
produces heat energy with hydrogen ion cell cell
blue flame without soot or (iii) Anode: Chloride ions release
pollutants. electron at the anode and • Consists of anode and cathode
form chlorine atom. This
3. (a) (i) Palm oil chlorine atom combined and (positive terminal and negative
(ii) Originate from living things form chlorine gas. terminal)
(b) (i) Vitamin E / Vitamin A Cathode: Copper(II) ions • Contain electrolyte
(ii) Obesity accept electron from the • Positive and negative ions move to
(c) (i) As solvent/Antiseptic/Fuel/To cathode and form copper electrode in the electrolyte
make alcoholic beverages atom at the cathode. • Electrons move from anode to
(ii) Causes liver cirrhosis/High cathode (negative terminal to
blood pressure/Stomach Q2 Position of ion in the electrochemical positive terminal)
ulcer series, concentration of ion in the
4. (a) P: Mesocarp / Pulp electrolyte, types of electrode use in Two different Carbon or metals
the electrolysis.
Q: Kernel metal immerse in that is different /
(b) Mesocarp and kernel (Any one) Q3 Electroplating, extraction of metals electrolyte same immerse in
and purification of metals
electrolyte
(c) Through extraction
(d) Production of soap, candle, Q4 Electric current Electric current
cooking oil, margarine (Any one) produce by produce chemical
Form
(e) Vitamin A/Vitamin E chemical reaction reaction
5
5. (a) (i) Methane gas A Rheostat
(ii) Carbon and hydrogen Does not use Use battery
(iii) Natural gas Copper strip battery
(b) (i) Combustion, respiration, (anode)
decay (Any one)
(ii) Photosynthesis Copper(II) Iron spoon Q4 Aluminium / zinc
(iii) Greenhouse effect / Global sulphate (cathode) • In a simple chemical cell, metal
warming solution electrode that is more reactive
6. (a) Saponification becomes the negative terminal and
release electron
(b) Sodium hydroxide solution
(c) Add sodium chloride to the • An iron spoon is used as the 6
mixture to separate soap from cathode and copper strip as the SPM Practice
the solution. Then, filter the anode Objective Questions
mixture to get the soap. • Rheostat is used to control the flow
of electric current 1. C 2. B 3. B 4. A 5. A
6. B 7. B 8. B 9. D
408
06 Ans Focus SC SPM.indd 408 24/02/2023 3:33 PM
Science SPM Answers
Subjective Questions Q3 (a) 7
1. (a) Electric energy → Chemical SPM Practice
energy Object F 2F Objective Questions
(b) (i) Bubbles of colourless gas 2F F Image 1. A 2. D 3. C 4. B 5. D
released
(ii) Hydrogen gas released 6. D 7. C 8. D 9. C 10. D
(c) (i) The copper electrode (b) 11. B 12. C 13. C 14. C 15. A
becomes thinner 16. C
(ii) The copper electrode Subjective Questions
corroded Object 2F F F 2F Image 1. (a) Dark
2. (a) Rubbing iron key with sandpaper (b) Move slowly the screen forwards
until the key becomes shinny. and backwards of the convex
(b) Using low and constant electric (c) lens until a sharp image of the
current bulb is formed on the screen
(c) Control the size of electric (c) u = 20 cm
current (d) Place the arrangement of
(d) • Silver atom at the anode Image apparatus towards a distant
release electron hence Object object outside the laboratory
becomes positively-charged 2F F F 2F such as a tree to replace the
silver ion. bulb
• Silver ions attracted to the iron
key cathode (d) 2. (a) When the distance of object
• Silver ions receive electron decreases, the distance of image
from the cathode and form increases. / When the distance
silver atom which deposited on Object of object decreases, the size of
the iron key. F Image F image increases.
(e) Prevent corrosion / making it (b) The image formed is real/
looks attractive inverted.
(c) The image becomes virtual and
Q4 (a) at the infinity.
Chapter (d) The image is at the focal point.
7 Light and Optics
Object F 2F 3. (a) Telescope
2F F Image (b) More light is allowed to enter
Checkpoint 7.1 resulting in the formation of
Q1 (a) Light rays is refracted and brighter image.
converged to a focus point after (c) As a magnifying glass to
reflection. (b) The image of object is real, magnified the first image from
(b) Light rays is refracted and inverted and magnified the objective lens
diverged after reflection. f
Checkpoint 7.2 o
Q2 (d) Enlargement = f
Q1 To form the first image that is real e
Optical terms Explanation and becomes the object to the 40
eyepiece lens = 5
Principal axis A straight line which
passes through the Q2 = 8 times
optical centre and is
perpendicular to the Optical Characteristics of (e) The final image observed is
axis of lens instruments image smaller. Form
4. (a) (i)
Optical centre, Point at the centre of Magnifying glass Virtual, upright and
O the lens; light travels magnified 5
through it without
refraction Camera Real, inverted and
diminished
Focal point, F A point on principal
axis. Light rays that Microscope Virtual, inverted Image
are parallel to principal and magnified
axis will converge or
diverge after passing Telescope Virtual, inverted
through certain lenses and magnified
(ii) Real, inverted and diminished
Image The distance between Closed circuit Real, inverted and (b) Y
distance, v the image and the television (CCTV) diminished (c) (i) Q: Diaphragm
optical centre (ii) Controls the amount light
that enters through it.
Q3 Spectacles and magnifying glass
409
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Science SPM Answers
5. (a) Microscope 2. (a) Chapter
(b) f , u , 2f 9 Space Technology
(c) L : Real / Inverted / Magnified
1
L : Virtual / Inverted compared to Checkpoint 9.1
2
object / Magnified
(d) Q1 (a)
Cellophane Retractable Cellophane 35,768 km Medium
tape section tape Earth
Orbit
Straw
Earth
(b) (i), (ii)
Eyepiece Manila card Objective
lens 500 km
Chapter
8 Force and Pressure
H L H
(b)
Checkpoint 8.1 N Geosynchronous
Q1 Water spills out in all direction Orbit
because pressure is uniformly
transmitted to all parts in the water. Straw Geostationary Equator
Q2 The pressure exerted in fluids in an Orbit
enclosed system will be uniformly (c) The flow of fluid in L is faster.
transmitted to other parts of fluid. (d) Bernoulli principle
Q3 • Hydraulic jack 3. (a) Aerofoil
• Hydraulic brake (b) S
• Dental chair
L
Q4 Q2 High Earth Orbit is an orbit located
Lift force at an altitude of 35,780 km and has
duration of orbit of more than 24
Thrust Resistance hours.
Q3
(c) The air flows at higher speed at
Weight the upper surface of the wings Apogee
compared to the bottom surface
of the wings. This makes the air
SPM Practice 8 pressure at the upper surface
of the wings is lower than the
Objective Questions bottom surface of the wings. The
1. D 2. B 3. A 4. B 5. B difference in pressure produces
lift force.
6. C 7. C 8. D 9. C 10. B (d) The house roof is blown by the Perigee
11. C 12. A 13. C storm Satellite
4. (a) Higher water level: X
Subjective Questions Lower water level: Y Q4 Hohmann transfer orbit is the orbit
Form
1. (a) Large piston can produce used to transfer satellites from the
greater force than the small (b) Velocity of water flow in section low orbit to the required high orbit.
5
piston. P is less than in section Q. Q5 Space junk have been left in the
(b) As the mass of weight m (c) Pressure in water in section P is space
higher than in section Q.
1
increases, the mass of weight m 2
also increases. (d) As velocity of water flow Checkpoint 9.2
(c) The larger the force is applied increases, pressure in water
on the small piston, the greater decreases. Q1 Global Positioning System, GPS is
the force produced by the large (e) a system that uses global navigation
piston. satellite network that provides
information about location, velocity
(d) Large piston B will move L and time standardisation.
downwards.
(e) Hydraulic jack // Car brake // Q2 Trilateration is a process of collecting
excavator // Dental chair H signals from three satellites to
calculate the locations, velocity
and height and hence produce the
information of locations.
410
06 Ans Focus SC SPM.indd 410 24/02/2023 3:33 PM
Science SPM Answers
Q3 GPS helps to prepare map details, iron nail, and no changes on the in a glucose solution at the
measure the duration accurately, steel nail. appropriate temperature.
track the locations and expedition. (b) (i) Manipulated variable: Iron
nail and steel nail // Types of Section B
SPM Practice 9 nails 5. (a) (i) Meiosis
(ii) Constant variables: Distilled (ii) Crossing over occurs at Q /
Objective Questions water // Duration of the Cell division occurs twice
1. C 2. B 3. B 4. C 5. B experiment (b) Crossing over
6. A 7. C (c) An alloy is a mixture of several (c) Four daughter cells
types of metals or a mixture of (d) (i) Mutation
Subjective Questions metal and non-metal by a certain (ii) Radioactive rays
1. (a) Hohmann transfer orbit percentage. 6. (a) (i) Gland M: Adrenaline
(b) (i), (ii) (d) The tower is rusting because (ii) Gland N: Insulin
iron is a pure metal that is easily
corroded. (b) Increased heart rate
2. (a) The presence of water (c) Via blood vessels
(b) (i) Plant Y is upright in water, (d) The N glands will work less to
plant X is not upright. secrete hormones to control
Low orbit (ii) Plant Y is supported by blood sugar levels, this in turn
Transfer the buoyancy of the water will make us healthier.
orbit around it. 7. (a) X: Positive ion
Earth (c) Hydrilla (b) X: 2.8.8.1 Y: 2.8.7
(d) The hollow stems contain air (c) To achieve stable electron
sacs to increase buoyancy arrangement
allowing the plant to be able to (d) Agree. Due to the low doses of
float on the surface of the water. radiation used, this will not bring
3. (a) Rubber X is longer than rubber negative impacts to our health. /
Y after being stretched. The potatoes will last longer.
(b) (i) Original length of rubber OR
sample Disagree, as gamma rays
High orbit
(ii) Length of rubber after being are obtained from radioactive
(c) Hohmann transfer orbit needs stretched / elasticity of material. This may cause
the least energy and fuel, rubber mutations to occur in the cell in
therefore the cost of launching (c) Rubber Y the long run.
can be saved. (d) Rubber X which is natural 8. (a) P: Nitrogen; Q: Hydrogen
(d) Expandable Launch Vehicle rubber, cannot withstand heat (b) Liquid
Reusable Launch Vehicle and can dissolve in organic (c) Factory A
2. (a) (i) Geostationary Orbit solvents such as petroleum. The iron catalyst will help
(ii) Geosynchronous Orbit Hence, it is not suitable to be increase the rate of reaction
(b) The duration of both orbits is the used as petrol pump hoses (d) As fertiliser
same with the duration of Earth’s particularly if exposed to the hot 9. (a) (i) Natural gas
rotation on its axis weather. (ii) Petroleum
(c) Appear stationary in the sky 4. (a) Yeast is more active at a higher (b) Fractional distillation
(d) Communication temperature. (c) Saturated hydrocarbons ✓
Example: MEASAT 1 // MEASAT 3 (b)
(d) Balloon
SPM Model Paper 40 Form
Paper 1 30 5
1. A 2. B 3. B 4. B 5. C Water
6. B 7. B 8. C 9. A 10. A Volume of gas produced (cm 3 ) bottle
11. B 12. D 13. B 14. D 15. D 20 Rice
16. A 17. C 18. C 19. C 20. D
21. B 22. C 23. A 24. B 25. A 10
26. A 27. D 28. B 29. D 30. D
31. A 32. C 33. B 34. D 35. C 0 10. (a) Pascal’s principle
40
45
35
36. B 37. D 38. D 39. B 40. A 30 Temperature (°C) 50 (b) According to Pascal’s principle,
the pressure applied to a fluid in
Paper 2 (c) When the temperature a closed system will be applied
Section A increases, the volume of carbon uniformly to every part of the
1. (a) There is rusting on the iron nail, dioxide produced increases. fluid.
and no changes on the steel (d) Yeast growth is a process that (c) No. Water can easily evaporate
nail. / There is brown residue causes the volume of gas to and air may dissolve into the
formed on the surface of the increase when yeast is placed water.
411
06 Ans Focus SC SPM.indd 411 24/02/2023 3:33 PM
Science SPM Answers
(d) decolourise (d) Electro-coagulation:
• Constant variable: Volume • Electro-coagulation is an
Small Large of water sample innovative technique to treat
piston piston (iii) Procedure: wastewater.
Small Water Large 1. Label the four reagent • Electro-coagulation applies
syringe syringe bottles P, Q, R and S. two processes, which are
Rubber 2. Fill up the bottles with electrolysis and coagulation.
tube water samples from • This method can avoid the
different sources: release of pollutants into the
P – Distilled water environment.
Q – Drain water The use of bacterial serum
Section C R – Pond water Lactobacillus sp.:
11. (a) What is the level of pollution for S – River water • Wastewater is treated using
3
the water samples collected from 3. Add 1 cm methylene blue culturable bacteria.
different sources? solution into each reagent • This treatment can get rid of
bottle using syringes.
(b) Water in location B is polluted. 4. Close the reagent bottle foul odours in the drainage
(c) (i) Aim: To study the level with its stopper. (Note: Do system.
of pollution for the water not shake the bottle.) 13. (a) Antibiotics are substances used
samples collected from 5. Store all four bottles in a to treat infections caused by
different sources. dark cupboard. bacteria.
(ii) Variables: 6. Record the time taken for Example: penicillin/streptomycin
• Manipulated variable: Type methylene blue solution to (b) Antiseptic is a chemical
of water samples decolourise. substance used to treat wounds
• Responding variable: on the skin by applying it to the
The time taken for wound to prevent infection by
methylene blue solution to microorganisms.
Disinfectants are chemicals used
to sterilise equipment and to
(iv) Tabulation of data: clean areas such as toilets and
Type of water Time taken for methylene blue hospital floors.
Bottle Antiseptics can be applied to
sample solution to decolourise
wounds while disinfectants
P Distilled water cannot.
(c) • Sterilisation using heat
Q Drain water • which is boiling and
R Pond water autoclaving.
• High temperatures above
S River water 100°C
• can kill microorganisms.
12. (a) Electrolysis is the process of (c) Electrolysis applications: Plating (d) No. The substances are
decomposition of a compound in 1. Clean the iron key and disinfectants which are
a molten or aqueous state into argentum plate with chemicals used to sterilise
its constituent elements when an sandpaper. equipment and to clean areas
electric current flows through it. 2. Put the iron key and such as toilets and hospital
Electrolysis applications: Plating argentum plate into the floors. Disinfectants should not
/ Extraction / Metal purification / argentum nitrate solution. be applied to wounds because
Electro-coagulation 3. Connect both the iron key they can damage body tissues.
(b) Aluminium cannot be extracted and the argentum plate
from the ore by the process with connecting wires to the
Form
of reduction by carbon. This is ammeter and battery.
because carbon is less reactive 4. Iron key as cathode,
5
than aluminium. Carbon is below argentum plate as anode.
aluminium in the metal reactivity 5. Let the electrolysis process
series. run for 10 minutes.
412
06 Ans Focus SC SPM.indd 412 24/02/2023 3:33 PM
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