Name: Class: Date:

Chapter 1 Introducing Science

Worksheet 1.1 For Science Matters Textbook Volume A, sections:

1.1 What is Science? 1.3 Life-long Skills and Attitudes
1.2 What is Technology?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. What is science?
A The study of how people live and work
B The study of matter, energy and their interactions
C The study of numbers
D The study of past events ( B )

2. Which of the following scientific applications benefits us?

A Creation of radioactive wastes B Excessive use of pesticides
C Invention of the light bulb D Production of nuclear bomb (

3. Which of the following is not one of the qualities of a good scientific thinking?
A Ability to accept other ideas
B Perseverance in obtaining an answer
C Sticking fast to old beliefs
D Willingness to work hard for a solution ( C )

4. A good scientist needs to think of .

A ways to become famous
B ways to solve a problem
C who noticed the problem first
D ways to make money out of new discoveries ( B )

5. What are the three main branches of science?

Biology, Chemistry and Physics

©
© 2007
2008 Marshall
Marshall Cavendish
Cavendish International
International (Singapore)
(Singapore) Pte
Pte Ltd
Ltd Introducing Science 1
6. Complete the table using the words in the box below. Each word may be used more
than once.

physicist biologist chemist astronomer

Thing(s) the scientist

The scientist is called a/an …
studies
Acids Chemist
A star Astronomer
A rainbow Physicist
The moon Astronomer
The speed of a bullet Physicist
Crystals Chemist
Starfish Biologist
A skeleton The Biologist
blue sky The Physicist
sky at night Astronomer

Map It Out

Complete the graphic organiser that follows the question below.

What are some of the qualities a scientist should have?

Creativity

Objectivity Keen observation

Qualities
of a good
scientist

Patience Open-mindedness

Perseverance

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

Challenge Yourself • 15 min •

Attempt the following questions within the

time allocated.

1. The Internet is a very useful

communication tool for people
around the world. But it can also
cause problems in society.

a) Describe some advantages and

disadvantages of using the Internet.

Advantages:
I can keep in touch with my

friends by e-mail. I can be close

to them even when they are very

far away. I don’t have to wait a

long time for a reply to my mails

like when I wrote and sent by

post.

I don’t have to depend on one textbook for my

learning as there are many websites on a topic.

Disadvantages:
Some of the things on the Net are

junk. I may learn the wrong

thing. I get hooked on games and

surfing and waste a lot of time.

Some websites teach people to do

wrong or harmful things. Books,

movies and musics get pirated.

b) List some ways to use the Internet safely

and wisely.
 need in case some of these
Use the
websites are not trustworthy.
Internet

only

when

necessar

y so that

time is

spent

wisely. /

Downloa

d or

install

program

mes

which

can

protect

your

computer

from

viruses. /

Check

more

than one

website

to obtain

the

informati
© 2007 Marshall Cavendish International (Singapore) Pte Ltd
on you
2. Scientific discoveries and advances in technology are supposed to make our lives
better. However, science often comprises the study of things around you for the
sake of knowing more about our world. This in itself seems like a good end to aim
for. Is it always necessary that what you learn in science is useful? Discuss.
Most discoveries have no use at the start. Einstein discovered that matter can be converted into energy

with his famous equation E = mc2. However, it was other scientists who made an atomic bomb out of

this discovery.

Sir Alexander Fleming noticed that the mould on his germ culture dishes killed the germs. However,

it was only later that the first antibiotic, called penicillin, was extracted from the mould to kill germs

and save lives. Hence, we will never know how useful a discovery is, until more work is done on it.

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

Name: Class: Date:

Worksheet 1.2 For Science Matters Textbook Volume A, section:

1.4 Where Do Scientists Work?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. An experiment is .
A a procedure carried out to find the truth
B a recipe for finding the best answer to a question
C any activity done on a laboratory table
D the gathering of information ( A )

2. Which of the following is an incorrect drawing of laboratory equipment?

A B C D ( C )

3. What is the apparatus shown on the right used for?

A Evaporating a liquid from a solution
B Measuring the volume of liquid
C Measuring volume of gas
D Separating different types of liquids ( B )

4. If you accidentally touch a corrosive acid, you should .

A leave it alone
B pour an alkali over your hand
C wash your hands with plenty of water
D wipe off the acid with a piece of tissue paper ( C )

5. What should you not do if some chemical gets into your mouth accidentally?
A Report the incident to your teacher
B Rinse your mouth with plenty of water
C Spit it out immediately
D Swallow it ( D )

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Introducing Science 5
6. The diagram below shows the set-up of an experiment.

V Test tube

W Beaker

X Wire gauze

Z Bunsen burner
Y Tripod stand

a) Name the apparatus labelled in the diagram above.

b) Suggest some reasons why the substance in V is heated in a water bath.

It might just melt when heated in hot water, but decompose when the test tube is heated directly on

the flame.

c) State the function of each X and Y.

X : To ensure heat is evenly distributed over the bottom of the beaker

Y : To support apparatus that is being heated

d) State three points to note when using Z.

Adjust the air hole opening to obtain the desired flame. Light up the match right before turning on

the gas or shortly after. Turn off the gas after use.

© 2008 Marshall Cavendish International (Singapore) Pte Ltd © 2007 Marshall Cavendish International (Singapore) Pte Science
Introducing Ltd 1
7. Many substances in the laboratory are hazardous. For such substances, hazard
symbols are shown on the container. Draw lines to match the symbols below with
the nature of the hazardous substance.

Symbol Hazard
Flammable:
• • Catches fire easily

Corrosive:
• • Substance will eat away other substances

Poisonous:
• • Substance that is harmful in small doses

Biohazardous:
• • Poisonous substance of a biological nature

Irritable:
• • Substance produces gases which irritate
the eyes, nose and throat
Explosive:
• • Will react violently when heated or struck

Map It Out

Complete the graphic organiser that follows the question below.

When you carry out a practical activity in the science laboratory, you may have to put
on some laboratory safety equipment. What are these equipment?

Rubber gloves Safety goggles

Laboratory safety
equipment

Laboratory coat

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

Challenge Yourself • 5 min •

Attempt the following question within the time

allocated.

Isaac had a science practical lesson

after recess. He was late for the lesson
and missed his teacher’s explanation
on how to handle corrosive chemicals.
However, he went ahead and carried
out the experiment. While doing the
experiment, he spilled some chemical
on the table and on his clothes, but
ignored it. After the lesson ended,
Isaac poured the chemical into the
sink. The apparatus were left in the
sink when he left.

a) What mistakes did Isaac make during the science

practical lesson?
1. When the chemical spilled on the table and on his clothes,
Isaac ignored it.

2. Isaac should not have poured the chemical into the sink
without washing it away with water.

3. Isaac should not leave the apparatus in the sink.

b) What should Isaac have done instead?

When Isaac spilled the chemical, he

should have reported the incident to

his teacher. He should have asked his

teacher if there was a need to dilute

the spill before wiping it off. He

should also ask his teacher if he

should immediately change his

clothes and wash them with plenty of

water. He should, at the first place,

wear a lab coat. After the lesson, Isaac

should pour the chemical into the sink

© 2007 Marshall Cavendish International (Singapore) Pte Ltd
and wash the test tube. He should then
dry

the

appar

atus

and

place

them

back

into

their

storag

place.
Name: Class: Date:

Worksheet 1.3 For Science Matters Textbook Volume A, section:

1.5 The Scientific Method

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following is not a scientific method?

A Doing experiments to test ideas
B Discussing ideas and making inferences
C Giving attention and sympathy
D Taking down notes and recording data ( C )

2. What is a hypothesis?
A An experiment
B A good guess based on observations
C A scientific statement
D A well-written article ( B )

3. When carrying out experiments, we make observations to .

A help us make use of our five senses
B help us gather data and information
C make sure we do not spill things accidentally
D predict the future ( B )

4. Which of the following is not a scientific experiment?

A Baking three cakes — one using one egg, one using two eggs and
one using three eggs — to see how the number of eggs used can affect
the cake
B Driving a car at different speeds — from 40 kph (kilometres per
hour) to 60 kph and to 80 kph — to find out the speed at which
the car can stop most smoothly.
C Dyeing your hair — yellow for a month, brown for the next
month, and then pink in the following month — to see which
colour looks best on you
D Watering three plants — one with a quarter cup of water,
one with half a cup of water and one with a full cup of water
— to
see which plant can survive the longest ( C )

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

5. Which of the following questions might be suitable for a scientific study?
A Can plants grow faster with the help of music?
B How can love overcome all odds?
C How many prime numbers are there between 1 and 2,000?
D What can be done to persuade people not to shoplift? ( A )

6. The scientific method is a step-by-step way of thinking or acting. When you apply
the scientific method, you analyse a problem or situation by moving through a
series of steps.

Stage Action
1 Observe: Make an observation.
2 Question: Ask a question.
3 Make a hypothesis: Attempt to answer the question with a guess.
4 Test: Carry out an experiment to test your hypothesis.
Check: Does the guess answer your question? If not, discard the
5 guess and repeat stages 3 and 4 with another guess. If it answers your
question, proceed to stage 6.
Conclude: If your guess answers the question, proceed to draw a
6 conclusion about your question.

Here are some statements that a person used to describe a scientific way of solving
a problem. Study each statement and identify which stage of the scientific method
the person was at. Write the number down in the last column of the table below.

Statement Stage
Rest is required to keep the mind alert. 6

Why do I feel sleepy when I study? 2

I feel sleepy when I study for long hours. 1

I take a ten-minute break for every hour I study. 4

Yes! I don’t feel sleepy anymore when I study. 5

Perhaps I feel sleepy when I study for long hours without rest. 3

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

 Map It Out

Complete the graphic organiser that follows the question below.

The scientific method comprises many steps. What are the most common steps in the
scientific method?

O bserving Questioning Hypothesising

E xperimenting

Rejecting
C oncluding
hypothesis

Theory

Challenge Yourself • 25 min •

Attempt the following questions within the time allocated.

1. A hypothesis is a good guess as to the reason for an observation.

For example, I observed that my sister’s shoes and umbrella were not at their
usual places. I formed several possible hypotheses:
1) She has gone out, taking her umbrella and wearing those shoes.
2) They are both drying in the sun because it rained today.
3) She gave both away to charity.
4) Her friend who stayed overnight borrowed both of them.

My next observation was that the shoes and the umbrella were found in the
dustbin, even though they were in good condition. From this I drew the conclusion
that:

All my previous hypotheses were wrong.

I proceed to form several new hypotheses, taking note of my observation:

1) She didn’t want them anymore and threw them away.
2) They fell into the dustbin by accident.
3) There is some other reason yet unknown.

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

 I then proceed to make further observations that either support or weaken each
hypothesis, discarding hypotheses that are wrong, until I arrive at the most likely
hypothesis.

Now you try!

Write down some simple hypotheses for the following observations.

a) You observe a leaf outside your window floating upwards in the

air.
A gust of wind blows it upwards.

Someone is raking leaves and has stirred this one up.

Someone is scattering leaves about and has thrown this one up.

b) You observe a withered plant that appears to be dying.

Someone forgot to water it.

Worms are eating away at its insides.

The fertiliser used was too strong and thus the plant is suffering from dehydration.

Some pest has eaten its roots.

c) You observe no stars in the night sky.

The sky is cloudy and all the stars are covered.

The moon is too bright and overpowers the starlight.

Light from the earth is scattered by dust in the atmosphere so that the scattered light is brighter

than the starlight even without clouds in the sky. (This is generally true in Singapore.)

d) You observe this evening’s sunset to be very red.

The atmosphere is laden with moisture. It is going to rain.

The scientific truth is that blue light has been scattered away from the white light coming from the

sun, so that only red light is left to be seen by the eye. The agents of scattering are dust particles

and water vapour in the atmosphere.

© 2008 Marshall Cavendish International (Singapore) Pte Ltd © 2007 Marshall Cavendish International (Singapore) Pte Science
Introducing Ltd 1
 Get It Right

Marie wanted to find out whether the amount of food consumed has an effect on weight
gain. So, she decided to test this out with mice.

She chose two mice from the same litter to try out her
hypothesis that the more food a mouse eats, the heavier
and fatter it is. The two mice she chose were of the same
gender and have the same weight. She fed one mouse
the usual amount she always fed her mice, which were
all thin. She fed the other mouse twice the amount
she gave to the first mouse. Every two days she
weighed the mice before giving them food.
She recorded their weights.

a) In this experiment, what is the independent variable?

The number of days since the experiment started

b) What is the dependent variable?

The weight of the mice

Recall the definitions of variables. Refer to the Science Matters Textbook, section 1.5 on
The Scientific Method.

c) Why did she weigh them before they were fed?

So that the weight of the food they ate will not be counted

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

d) Why did she choose to feed two mice?
So that the first mouse, eating the usual amount of food, became the control to compare with the second

mouse.

e) Why did she weigh the mice at the start of the experiment and choose two from the
same litter, of the same gender, and of the same weight?
To keep the two mice as similar as possible. In this way, we cannot say that one mouse grew fatter

because it came from a family of fat mice, or because it was a male, or that it was fat to start with.

Analyse what is required in an experiment. Ask yourself, “Is the same starting
condition required?” and “What is the control set-up or condition?”

f) Scientific studies on mice have shown that in similar experiments done with
many mice, the thin mice lived longer, were healthier and were more intelligent.
From the results of these studies, what inference can you make on the health of
human beings?
We should avoid overeating so that we will be healthier in the long run.

Predict what would happen to a human being who eats more than what he or she
should have.

© 2007 Marshall Cavendish International (Singapore) Pte Ltd

Name: Class: Date:

Chapter 2 Measurement and Units

Worksheet 2.1 For Science Matters Textbook Volume A, sections:

2.1 The Importance of Accurate 2.3 Measuring Length
Measurement and Standard Units
2.4 Measuring Area
2.2 Units of Measurement

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. You are given four instruments, A, B, C and D.

A B

C D

Which instrument would you use to measure each of the following objects?

a) Length of a book ( A )

b) Thickness of a book ( D )

c) Height of a cupboard ( C )

d) Length of a pendulum ( A )

e) Width of a hole in a bowling ball ( D )

f) Waist measurement of a person ( B )

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Measurement and Units 1
2. The external diameter of a pipe was measured. The figure below shows the reading
on the vernier calipers. What is the external diameter of the pipe?
1 2 A 1.00 cm
B 1.03 cm
C 1.30 cm
D 3.00 cm ( B )
5

3. The diameter of a thin wire was measured with a pair of vernier calipers. Figure A
shows the reading when the wire was measured. Figure B shows the reading when
the wire was removed and the jaws were fully closed.

1 2 0 1

5 5
Figure A Figure B

What is the diameter of the wire?

A 0.25 cm B 0.61 cm
C 0.93 cm D 1.53 cm ( B

4. State the readings given by the following vernier scales:

a) 11 12 b) 7

5 5

10.92 cm 6.59 cm
Answer: Answer:

5. Convert the following quantities into the units given.

a) 1.25 km = 1.25 × 1,000 m= 1,250 m

b) 850 m = 850 × 0.001 km = 0.85 km

c) 120 m = 120 × 100 cm = 12,000 cm

d) 15 cm = 15 × 0.001 m= 0.015 m
6. The outline of a flower is shown in the grid below. Find its area.

Key
= 2 unit2
No. of ticks = 77

Area = 154 unit2

7. Outline how you would go about obtaining the most accurate reading for the
following:
a) Height of a person
Paste a measuring tape on the wall, with the zero mark at the floor level. Ask the person to stand

against the measuring tape. Slide a flat folder (or book) onto the person’s head and take the

reading

where the folder touches the tape. This is to avoid parallax error.

b) Depth of a hole in the wall made by a drill

Insert the tail end of the vernier calipers to the bottom of the hole and take readings from the vernier

calipers. Check for zero error and take an average of several readings.

c) Diameter of a bowling ball [Hint: Use the formula for calculating circumference
to help you.]
Measure the circumference of the ball with a measuring tape. Take an average of several readings at

different positions. Calculate the diameter, d, with the following formula: Circumference, c = π d.

d) Thickness of a razorblade, given a packet of ten

Measure the thickness of the pack of razorblades with a pair of vernier calipers or a micrometer.

Divide by ten to get the average thickness of each blade.

8. You are given a cup (shown on the right), a flexible measuring tape, vernier calipers
and a ruler.
a) What would you use to measure the circumference A
of the band around the mouth of the cup?
Measuring tape
B
b) What would you use to measure the depth of the cup?
C
Ruler/vernier calipers (with its tail)
 c) What would you use to measure the average internal diameter of the cup?
Use the inside jaws of the calipers to grip the internal wall of the cup at B.

d) What would you use to measure the thickness of the cup at its mouth?
Vernier calipers with jaws gripping the thickness of the cup at its mouth (at A).

9. Figure A shows the reading of a pair of vernier calipers when it is closed fully.
Figure B shows the reading when there is a steel pipe clamped between its jaws.
0 1 5 6

5 5
Figure A Figure B
+ 0.03 cm
a) What is the zero error?

b) What is the diameter of the steel pipe?

Reading on figure B = 4.63 cm
Hence, diameter = 4.63 – (+0.03) = 4.60 cm

c) What would the answers be to parts (a) and (b), if the 0 1

zero error had been different, as shown in figure C?

The new zero error = – 0.03 cm (by reading backwards from “10”)
5
The diameter of the steel pipe = 4.63 cm – (–0.03 cm) Figure C
= 4.63 + 0.03 = 4.66 cm

Challenge Yourself • 5 min •

Attempt the following question within the time allocated.

a) What is the length of this egg?

Reading on left = 0.9 cm

3.8 cm
Reading on right =

Length of egg = 3.8 cm – 0.9 cm = 2.9 cm

b) If you were looking at a real egg instead of a

picture, explain how you can minimise parallax
error when measuring the diameter of the egg. 0 cm 1 2 3 4

Use a set-square to align the ends of the egg with the 99 98 97 9

6
scale readings.
Name: Class: Date:

Worksheet 2.2 For Science Matters Textbook Volume A, sections:

2.5 Measuring Volume 2.7 What is Density?
2.6 What is Mass? 2.8 Temperature

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Mr Ng is rebuilding his home. When he designs his garden hedge, his swimming
pool and grass carpet for his garden, he is likely to be dealing with measurements in
respectively.
A area, length and volume B length, volume and area
C volume, area and length D volume, length and area ( B )

2. Convert the given readings into new units by completing the following table.

litre ( ) millilitre (m ) cubic centimetre (cm3) cubic metre (m3)

a) 0.063 63.0 63.0 0.000063
b) 2.03 2,030 2,030 0.00203
c) 0.025 25.0 25.0 0.000025

3. How many cartons of orange juice, each marked 1.5 , are needed to fill up a glass
tank at a drink stall if the tank measures 40 cm × 50 cm × 30 cm?
Volume of tank = (40 × 50 × 30) cm3 = 60,000 cm3 = 60
60
Number of cartons of orange juice needed = = 40 cartons
1.5

4. a) Which material is the densest, A, B or C?

1 cm3 1 cm3 1 cm3

7.86 g 19.6 g 11.3 g

A B C

B
Answer:
masses
How did you arrive at your answer? I compared their .
 b) Which material is denser, D or E?

4 cm

120 g 2 cm
120 g
2 cm 1.5 cm
5 cm 5 cm
D E

E
Answer:

How did you arrive at your answer? I compared their volumes .

c) Which material is the densest, F, G or H?

320 g 440 g 80 g

F 40 cm3 G 40 cm3 H 40 cm3

Answer: G

How did you arrive at your answer? I compared their masses .

d) Which material is denser, I or J?

0.2 m 0.5 m

0.1 m 0.1 m
16 kg 40 kg
0.1 m 0.1 m
I J

Answer: They have the same density.

How did you arrive at your answer? I calculated the density of each

of the two blocks using their masses and volumes . I then

compared their densities .

5. In the two vessels of water, which of the objects marked A, B, C, D, E, and F are:

a) denser than water? C and F

A D
b) less dense than water? A and D E
B
c) as dense as water? B and E C F
6. The mass of a stone is measured as shown. The stone is attached to a string and
lowered into a cylinder of water.

a) What is the volume of the stone?

10 cm3

b) What is the density of the stone?

Mass
Density =
Volume
50 g
=
10 cm3
= 5 g/cm3

c) Why can’t you use this method to find the

density of a piece of cork? cm3 cm3

50 50

Cork floats on water and will not displace a volume 40 40

30 30
of water equal to its volume. Hence, the volume
20 20

10 10
measured is not accurate.

7. Six substances, solids and liquids, were put into a tall cylinder and allowed to settle.
They are marked as A, B, C, D, E and F in the diagram. In this table, fill in the
correct letters against the names of the substances.

Substance Density (g/cm3) Letter

Oil 0.8 B A
B
Polythene* 0.9 C
C
Steel 8.0 E
D
Water 1.0 D
E
Mercury 13.6 F
F
Cork 0.2 A
* A plastic material
Challenge Yourself • 25 min •

Attempt the following questions

within the time allocated.

1. Three balls have densities of 0.9

g/cm3, 1.1 g/cm3 and 1.3 g/cm3
respectively. They are immersed
in turn in four beakers carrying
different liquids.

A B
C D

a) Which of these beakers holds a

liquid of density 1.2 g/cm3 ?
( C )

b) The other beakers hold oil of

density 0.8 g/cm3, water of
density 1.0 g/cm3 and
mercury of density 13.6 g/cm3.
These are shown respectively
as .
A A, B and D
C C, D and B

2. Mercury, cooking oil and water are

placed together in a tall glass jar.
Their densities are 13.6 g/cm3, 0.8
g/cm3 and 1.0 g/cm3 respectively.
Here they are shown together with
a fourth layer, which may either be
a cylindrical slab of wood in (a) or
a thick oil in (b) and (c).

a) If a cylindrical slab of wood

 (having a density
of 1.12 g/cm3) with
the same diameter
as the internal
diameter of the
glass jar is the
fourth layer in the
jar,
which is the most
likely position it will
occupy?
( C )

b) If thick oil of
density 0.98 g/cm3
that does not mix
with the other
liquids is the fourth
layer in the glass
jar, which position
will it occupy ?
( B )

c) An iron nail of
density 7.8 g/cm3 is
then dropped into
the glass jar with the
thick oil as the
fourth layer. The
nail would finally
sink to a level at the
bottom of one
of the liquids — A, B,
C, or D. Which liquid
is it?
( C )
3. Isaac bought a few packets of sea salt and some aquarium fish
that were put in a tightly knotted polythene bag filled
with water. He was about to untie the knot to release
the fish into a deep tank of water when the polythene
bag slipped and fell to the bottom of the tank.

His arms are not long enough to reach the bag and he has no tools with him. What
can Isaac do to get the bag out of the tank?
He can put some of the sea salt into the tank, and stir the water such that the salt dissolves. The density

of the salt solution will be greater than that of the polythene bag filled with water. The polythene bag

will then float to the surface.

4. a) Using the scale below, find the diameters of circles A and B.

B
A

Left reading Right reading Diameter

(cm) (cm) (cm)
A 1.3 3.3 2.0
0 cm 1 2 3 4 5 6 7 8 B 4.9 7.4 2.5

b) If circle A is the cross-section of sphere X and circle B is the cross-section

of sphere Y, find the volumes of these spheres.
4
Volume of sphere X = ( ) (π 13) = 4.19 cm3
3
3 3
Volume of sphere Y = ( 4 ) (π 1.25 ) = 8.18 cm
3

c) Take note of the volumes of the two spheres, X and Y. Make an observation
on how one sphere is different from the other in terms of its cross-sectional
diameter and volume.
What can you say about the change in the volume of the spheres as compared
to the change in the cross-sectional diameter?
The diameter of sphere Y is only slightly larger than that of sphere X, but its volume is about twice

that of sphere A.

d) How can you apply this observation in everyday life?

When shopping, choose the slightly larger round objects (e.g. fruits, eggs, fishball and potatoes)

if they are sold per piece. You may get double the volume for the same price.
 Get It Right

The diagram shows the cross-section of a large iron pipe.

D2
Its internal and external diameters are shown.

a) What instrument would you use to measure these diameters?

Vernier calipers
D1
b) Sketch the iron pipe in these diagrams to show how the instrument is used to
measure the diameters.

Measuring D1 Measuring D2

c) The corresponding settings of the vernier scale obtained when measuring external
and internal diameters are shown below.
10 11 8 9

5 5
D1 D2

Read and record the diameters.

i) External diameter = 10.07 cm

ii) Internal diameter = 8.22 cm

d) Calculate the value of the thickness of the pipe from these readings.
External diameter – Internal diameter
Thickness of the pipe =
2
10.07 – 8.22
=
2
1.85
=
2
= 0.925 cm

Refer to the Science Matters Textbook Volume A, section 2.3 on Measuring Length.

24 Measurement and Units © 2008 Marshall Cavendish International (Singapore) Pte Ltd
 Get It Right

Here is a diagram showing the earth going round the sun. The radius of the earth’s
circular orbit is 150,000,000 km. The planet Jupiter also orbits around the sun. One of its
moons, Io, is shown below.

earth
A

Jupiter and its moon,

Io, seen from earth
B
the sun

When the earth was at point A (near to Jupiter), the Danish Astronomer, Ole Romer,
observed the moon Io going behind Jupiter (an eclipse). This occurred in a regular
pattern such that Romer could predict exactly when it would happen.

However, when the earth was at point B six months later, Romer noticed that the
eclipse of this moon was observed 1,000 seconds late. From this observation, Romer was
able to calculate the speed of light.

a) Why do you think there was a 1,000 seconds delay in Romer’s observation of the
eclipse?
Light from Io travelled a greater distance when the earth was at point B than when it was at point A.

Distance = speed x time. When distance increases, time taken by an object to travel at
a constant speed also increases. This causes the time delay.

34 Time, Rate and Speed © 2008 Marshall Cavendish International (Singapore) Pte Ltd
b) Calculate the extra distance travelled by light from the moon Io to point B as
compared to when it travelled to point A.
Extra distance travelled by light is equal to the diameter of the earth’s orbital circumference.

Extra distance travelled by light = 2 × 150,000,000 km

= 300,000,000 km

Extra distance travelled by light is the difference between the distance light
travelled from the moon to point B and the distance it travelled to point A.

c) What is the speed of light?

300,000,000 km
Speed of light =
1,000 s
= 300,000 km/s
= 300,000,000 m/s

Use the value of time delay and extra distance travelled to calculate the speed of light.
This is because the values of time taken for light to travel from the moon to A and to B
were not known.
Name: Class: Date:

Chapter 3 Time, Rate and Speed

Worksheet 3.1 For Science Matters Textbook Volume A, sections:

3.1 Measuring Time
3.2 What is Rate?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. To measure the time of an athlete’s performance, the best equipment to use is

.
A a clock B an egg-timer
C a watch D a stopwatch ( D )

2. What can you use to measure the time required to cook broccoli?
A An egg-timer B A pendulum
C A stopwatch D Any of the above ( D )

3. A man board a bus at 12.48 p.m. and alighted at the end of his journey
at 2.15 p.m. How long did the journey take?
A 1 h 3 min B 1 h 27 min
C 2 h 33 min D 10 h 33 min ( B )

4. The reading of the stopwatch is .

4 5
29 30 1
28 2 35
26
27
59
60 31
3
4
6
57 58 32
14 15 1 33 5
25 56 13 2
34
12 3
55 11 4 35
24 6
54 10 5
9 6 36
8 7
23 53 37 7
22 52 38 8
51
21 39
50 9
40
20 49
48
42
41 10 A 5 min
19 47 43 11
18
46 45 44
12 B 5 min 4 s
17 13
16 15 14 C 5 min 5.3 s
D 5 min 35.3 s ( D )

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Time, Rate and Speed 1
5. Which of the following statements does not express a rate?
A The heart beats seventy times per minute.
B The leg gets cramped every time it exercises.
C The lungs breathe in and out 20 times per minute.
D The stomach gets food four times a day. ( B )

6. Which of the following statements does not express a frequency?

A He tidies the attic once in a blue moon.
B My mother goes to her hairdresser once a month.
C The MRT train comes once every seven minutes.
D We go swimming once a week. ( A )

7. A drip machine delivers drops of liquid medicine, each drop having a volume of
0.005 m . A nurse was asked to give a patient medication at the rate of 6 m per
hour.

a) How many drops of liquid medicine are delivered into the patient’s body in one
hour?
6m
In one hour, the total number of drops required = = 1,200 drops
0.005 m

b) How many drops of medicine are delivered into the patient’s body in one
minute?

1 hour = 60 minutes

Number of drops delivered in one minute = 1,200 drops = 20 drops

60

8. The following is a list of Geno’s monthly expenses.

• Weekly servicing of his parts, per visit: $120

• Motor oil for knee and elbow joints: $60
• Burnt fuses, bulbs and wiring: $30
• Portable batteries: $24

How much money does Geno spend per week?

Total monthly expenses = ($120 × 4) + $60 + $30 + $24
= $480 + $60 + $30 + $24
= $594
1 month = 4 weeks
$594
Therefore, Geno’s total expenses per week = = $148.50
4
9. At the chocolate factory, Amy can pack 1,410 chocolates per hour. Bob can pack
408 boxes in an 8-hour working day. If each box holds 30 chocolates, who can pack
faster?

1,410
Number of boxes Amy can pack per hour = = 47 boxes
30
408
Number of boxes Bob can pack per hour = = 51 boxes
8

Therefore, Bob can pack faster.

Map It Out

Complete the graphic organiser that follows the question below.

Time can be measured in many units. List some of these units.

Years

Seconds Months

Units of
time Weeks

Minutes

Days

Hours
Challenge Yourself • 10 min •

Attempt the following questions

within the time allocated.

1. A newborn baby was measured to

be 50 cm in length from head to
toe. In 16 years, the baby grew to
1.8 m in height. How much did the
child grow on average per year?
A 2 cm
C 8 cm

2. The m
kitche e
n tap
is
drippi
ng
again.
If
every
drop is
0.05
and it
fills up
a 1.5
bottle
in a
day,
how
many
drops
ar
forme
d per
minute
?

1.5 mber of drops per

= day =
1.5
×
1,0
00
m
=
1,
50
0
m

Nu
 1,500 m
= 30,000 drops day?
0.05 m
$32
An = $4
1 na’s 8
da ear
y nin
3
= gs
0
24 per
,
ho hou
0
urs r =
0
=
0 Aniza’s earnings per hour = $ 5
24
×
d
60 $
r 1
mi
o ,
nu
p 0
tes 5
s
= 0
1
minutes Al’s earnings per hour = = $4.40
, (30 × 8)
4 The person who is best paid by the hour is
Nu
4 Aniza.
mb
0
er
of
dro
ps
for
me
d
per
mi
nut
e=
=
20.8
≈ 21
drop
s

3. During the holidays,

Anna worked as a
salesgirl for $32 per day,
from 9 a.m. to 5 p.m.
every day. Her parents
paid her sister Aniza $5
per hour to do chores
and help out at their
store for six hours every
day. Their brother Al
works from 9 a.m. to 5
p.m. and gets paid
$1,050 per month of 30
days. Who is best paid
by the hour, assuming
that they work every
Name: Class: Date:

Worksheet 3.2 For Science Matters Textbook Volume A, section:

3.3 Speed

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. To measure the average speed of the wind, Isaac threw

a sheet of paper in the air and watched the second hand
of his wristwatch. As Isaac counted, the wind blew the
sheet of paper directly towards Marie, who was 50
metre away from Isaac. He stopped counting when
Marie held out her hand to show that the paper had
passed her. Isaac counted only 4 seconds. What was
the average speed of the wind?
A 10 m/s B 12 m/s
C 25 m/s D 50 m/s
( B )

2. Thunder occurs when the lightning strikes.

a) Light travels at 300,000,000 m/s. When lightning strikes 2 km away from your
house, you will see the lightning flash .
A 2 s later B 4 s later
C 6 s later D almost immediately ( D )

b) Sound travels at 330 m/s. From 2 km away, you will hear the thunder .
A 2 s later B 4 s later
C 6 s later D almost immediately ( C )

3. A lorry travelled at 60 km/h for 15 min. It then slowed down to travel at 46 km/h for
45 min. What was the total distance covered by the lorry?
A 49.5 km B 75.0 km
C 94.5 km D 104.5 km ( A )

4. A car travelled 60 km in 40 min and then travelled another 90 km in 1 h. What is the

average speed of the car?
A 60 km/h B 90 km/h
C 75 km/h D 100 km/h ( B )
5. If Marie cycles 2.5 kilometres to her friend’s house from her home in 12 minutes
and then cycles home quickly in 8 minutes, what is her average speed in km/h?

Total distance travelled = 2.5 km + 2.5 km = 5.0 km

Total time taken to travel this distance = 12 min + 8 min = 20 min = 1/3 h

Total distance 5.0 km

Average speed =Total time taken = 1/3 h = 15 km/h

6. The MRT train doors closed 2 minutes after Isaac got in. The train then moved off,
travelled fast and then slowed down. It stopped 6 minutes later, at the next station,
6.7 km away. Isaac waited half a minute before getting out of the train due to the
crowd.

What was the average speed of his journey? Give your answer in m/s.

Total time of journey while Isaac was on the train = (2 + 6 + 0.5) min
= 8.5 min
6,700 m
Average speed = = 13.1 m/s
(8.5 × 60 s)

7. Becky took 45.2 s to complete a 400 m race.

a) What was her average speed in m/s?

400 m
Her average speed =
45.2 s
= 8.85 m/s

b) What is 1 m/s in km/h? Therefore, what was Becky’s speed in km/h?

0.001 km = 3.6 km/h

1 m/s =
1/3,600 h

Becky’s speed = 8.85 × 3.6 km/h

= 31.86 km/h

8. A very light arrow moving at 96 m/s takes 1.5 s to fly from the bow to hit a target.
How far away was the target?

Distance moved = 96 × 1.5 = 144 m

 Map It Out

Complete the graphic organiser that follows the question below.

Rate is applied in many ways. One example is flow rate. Flow rate is the change in the
volume of liquid per unit time. How does flow rate differ from speed?

Flow rate Speed

volume The change distance

The change of bitter in
per unit time . travelled per unit time .
red

Related to a flowing fluid Related to a moving object

Do not react
Volume of liquid Distance
Flow rate = Speed =
Time Time

S. I. unit: m3/s S. I. unit: m/s

Challenge Yourself • 25 min •

Attempt the following questions within the time allocated.

22
1. The earth’s radius is about 6,300 km. Take π to be 7 and Singapore to be on the
equator. Calculate the speed with which we are moving round the axis of the earth.
[Hint: One round about the axis of the earth = one day = 24 hours]
22
Distance = 2πr = 2 × 7 × 6,300 km = 39,600,000 m
Time taken = 24 × 60 × 60 = 86,400 s
Distance = 39,600,000
Speed = Time taken 86,400 = 458 m/s
Singapore

2.
Radio signals are similar to light. They also travel at 300,000,000 m/s.
These signals can also be reflected off the surfaces of objects. We use
these signals to find out how far away these objects are.
 Geno has a radar that sends out or receives a very short and sharp radio signal.
One day, he saw an unidentified flying object (UFO) in the distant sky over the
horizon and quickly sent out his radio signal. Soon after, his radar received the
reflected signal. The time interval between these signals was 1.8 ms.

a) Explain why there were two signals.

The first radio signal was the one sent out to the UFO. The second signal was the one reflected and

travelled back to Geno.

b) Geno used the time interval between the two signals to tell how far away the UFO
was. Show his calculations.

Let the UFO be at a distance D away. At the speed of light, the radio signal travelled 2D during
the time interval between the two signals.
Distance moved
= Speed
Time taken
2D
= 300,000,000 m/s
0.0018 s
2D = 300,000,000 x 0.0018 = 540,000 m
D = 270 km

Hence, the UFO was 270 km away from Geno.

3. Marie and Isaac were timekeepers on Sports Day. Marie sat by the finishing line,
200 m away from the starting line. Isaac stood by the starting line to time the 200 m
race. As soon as Isaac and Marie heard the starter’s gun, they each started their
stopwatches. They stopped their stopwatches when the winner reached the
finishing line. Isaac’s stopwatch read 23.12 s while Marie’s stopwatch read 22.54 s.

a) If we take Isaac’s time to be correct, what was the average speed of the
winner?

200 m = 8.65 m/s

23.12 s

b) Marie realised that the sound of the gun took time to travel. By the time
she heard the gun, it was too late, and the participants had already started
running. How much time did the sound of the gun take to travel to Marie?

23.12 – 22.54 = 0.58 s

c) Using your answer in part (b), calculate the speed of sound.

200 m = 345 m/s

0.58 s
Name: Class: Date:

Chapter 4 Classification of Matter

Worksheet 4.1 For Science Matters Textbook Volume A, sections:

4.1 What is Classification?
4.2 Types of Physical Properties

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following is not an example of classification?

A Arranging groceries in a shop according to their prices
B Planning a menu according to food available in the refrigerator
C Separating cutlery according to their sizes
D Sorting books according to their subjects ( B )

2. The diagram below shows how a group of buttons are classified.

How are they classified?

A They are classified according to the number of holes they have.
B They are grouped according to the types of edges they have.
C They are classified based on their colours.
D They are grouped based on their functions. ( B )

3. Which of the following is not a physical property of substances?

A Electrical conductivity B Flexibility
C Source of a substance D Strength ( C )

4. What is classification? How is classification useful to us?

Classification is the process of grouping things according to their similar properties.

Classification allows us to group things more systematically. It is a useful and systematic way to help us

study the world around us.

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Classification of Matter 1

5. Match the following properties with their definitions.
Property Definition
a) Strength • • Measure of how readily electricity
passes through a material

b) Hardness • • Ability to support a heavy load

without breaking

c) Density • • Ratio of the mass of a substance to

its volume

d) Flexibility • • Constant temperature at which

matter changes from liquid to gas

e) Electrical • • Ability to bend without breaking and

conductivity return to an object’s original shape
and size

f) Heat conductivity • • Ability to withstand wear and

scratches

g) Boiling point • • Measure of how readily heat passes

through a material

h) Melting point • • Constant temperature at which

matter changes from solid to liquid

6. List the properties of the materials that are important for the following objects.

a) Carpets to layer wooden floors of houses

in cold countries
Poor heat conductor, strong, flexible, soft, can be

woven into different shapes and sizes.

b) Ice blocks for walls of igloos

Poor heat conductor, strong, can be cut to different

shapes and sizes.

c) Steel for structures of bridges

Hard and strong, malleable (can be bent and

moulded into shapes).

Challenge Yourself • 20 min •

Attempt the following questions within the time allocated.

1. Use the information below to list the order of

hardness of materials W, X, Y and Z, starting
with the hardest substance.

• W is left with a mark when X is rubbed with it.

• Y is scratched by all the other three materials.
• When rubbed with Z, all three materials are left
with a mark.

A W, X, Y, Z B X, Y, Z, W
C Z, X, W, Y D Z, Y, X, W
( C )

2. The table below shows the melting and boiling

points of substances investigated by three
students.

Student Melting point (°C)

Tracy –12
Sara 23
Ben –12

Which of the following is true?

A They investigated three different substances.
B They investigated the same substance.
C Tracy and Ben investigated the same substance.
D The substance investigated by Sara is solid at 28 °C.
( C )

3. The diagram below shows how good

conductors of electricity and good insulators
of electricity can be used together.

a) Explain how good electrical conductors and

insulators complement each other in the
object shown above.
The

copper

wire

conducts

electricit

y. The

plastic

insulatio

prevents

leakage

of

electricit

y to flow

to other

objects

that are

in

contact

with the

cable; it

also

prevents

electric

shock.
 b) Give another example of an appliance that uses good electrical conductors and
insulators in a similar way.
Power plug

4. You are a sales representative of a company manufacturing protective clothing

for firemen. Sketch a short advertisement on the protective clothing. In your
advertisement, state the properties of the materials that are used for your
products.

Explain why the materials are important for their functions.

Poor heat conductivity (insulator – heat proof), fire resistant (fire proof), lightweight and flexible (helps

fireman to move about quickly), high melting point (withstand high temperatures).
Name: Class: Date:

Worksheet 4.2 For Science Matters Textbook Volume A, section:

4.3 Types of Materials

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Silk is classified as a .
A ceramic B fibre
C metal D plastic ( B )

2. Plastics are made from .

A crude oil B fibres
C minerals D plants ( A )

3. Which of the following is not a property which makes iron widely used?
A Corrodes easily B Good electrical conductivity
C Malleability D Strength ( A )

4. What type of material is polythene classified as?

A Ceramics B Fibres
C Glass D Plastics ( D )

5. Which materials demonstrate the following properties?

• conduct electricity well • hard and strong

• ductile • malleable

A Fibres B Glass
C Metals D Plastics ( C )

6. What is the source of each of the following materials?

a) Glass: Made of silica, soda ash, and lime.

b) Ceramics: Produced using clay and other minerals from the earth.

c) Metals: Found in the earth’s crust.

d) Plastics: Made from crude oil.

e) Fibres: Made from natural (e.g. plants, crude oil) or artificial substances (e.g. chemicals).
Challenge Yourself • 10 min •

Attempt the following questions

within the time allocated.

1. The properties of a material are

given below.

• conducts heat well

• does not rust
• has a high melting point

Which of the following objects is

made of this material?
A

C
D

( D )

2. Why are we strongly encouraged to

reuse, recycle or reduce the use of
plastics?
Plastics are non-biodegradable and do not
corrode easily. They are made from crude
oil, which will

eventually run out.

3. The diagram below shows a frying

pan, being used to cook an egg.

a) What are the two different

materials used to make various
parts of this pan?
 The pan is metallic and
the handle is plastic.

b) Why are those

materials used?
Metal is used because it

conducts heat well. Food

can be heated easily.

Plastic is used because it

does not conduct heat. It

prevents heat from

flowing to the hand.

Name: Class: Date:

Worksheet 4.3 For Science Matters Textbook Volume A, section:

4.4 Choosing the Right Material

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. To select a material to make a water bottle, which of the following properties are
important?
I Does not corrode
II Waterproof
III Transparent
A I B II
C III D I and II ( D

2. Which property would you need to consider when choosing a gas

used to fill the gas balloons?
A Colourlessness
B Density
C Melting point
D Transparency ( B )

3. Why are drinking mugs made from ceramics?

A They are easily coloured.
B They are poor conductors of heat.
C They do not corrode.
D They do not melt easily. ( B )

4. Write down at least two uses for each of the materials below.
Floor and wall tiles/ Kitchenware / Decorative vases / Space shuttle tiles / Engine
a) Ceramics:
components / Catalytic converters / Artificial bones and teeth / Electronic components.

b) Fibres: Kitchen gloves / Clothing / Curtain material / Ropes / Carpets / Rugs.

5. Study the following table and answer the questions that follow.

Heat
Transparency Strength Melting point
conductivity
Material A Transparent Moderate Good High
Material B Transparent Moderate Poor Low
Material C Opaque High Good High

a) Which material (A, B or C) is most suitable for making the containers used in
the science laboratory? Explain.
Material A.

Transparent — allows us to observe what is happening in the apparatus.

Good heat conductivity & high melting point — allows heating of substances/chemicals without

melting.

b) State another property that is important before you decide on the choice of a
material for making the containers used in the science laboratory. Explain.
Resistance to chemicals — the material used to make apparatus should not react with chemicals

used in the laboratory.

c) Suggest possible identities of materials A and B.

Substance A – Glass; Substance B – Plastics.

6. Look at the trawling net used to catch fish below.

plastic balls

metal balls

Explain why plastic balls and metal balls are used.

Plastic balls are less dense than water. Therefore, they can float. This helps the fisherman to identify the

position of the net. Metal balls are denser than water. Therefore, they sink. This helps spreading out the

net.
 Map It Out

Complete the graphic organiser that follows the question below.

What are the different non-metallic materials? Give two examples of objects made up of
each material.

Non-metals

Ceramics Glass Plastics Fibre

• Vase • Window • Water bottle • Clothes

• Plate • Spectacles • Pail • Bed sheet

Challenge Yourself • 25 min •

Attempt the following questions within the time allocated.

1. Which is the most important reason for the use of plastics in the making of cooler
boxes?

A Plastics are lightweight.

B Plastics are poor heat conductors; hence, they do not allow heat to be
transferred into the boxes easily.
C They are durable and can last for a long time.
D They can be coloured brightly. ( B )
2. From the table below, which material would be most suitable for making overhead
electric cables?

Relative electrical conductivity

Material Density
(measured against copper – value of 100)
A 59 2.7
B 100 8.9
C 17.7 7.85
D 1.66 13.6 ( A )

3. Isaac heated a piece of iron on a Bunsen flame and placed the hot metal
immediately into a container. To his horror, the container started to melt.

a) Suggest why the container melted. Name a possible material for this container.
The melting point is too low, lower than the temperature of the hot iron. A possible material for this

container is plastic.

b) Suggest another material for the container so that it will not melt if the same
process is carried out. Why did you choose it?
Ceramic or glass. It has a very high melting point.

c) Suggest the materials which made up the equipment that Isaac had used to
hold the hot piece of iron in the flame of the Bunsen burner.
Handle — made of wood or plastic (insulator).

The part holding the iron — made of metal or ceramic (high melting point).

4. One of the first synthetic (man-made) substance, Bakelite, was discovered in 1907,
by Leo Baekeland, a New York chemist. Bakelite is a material that retains its shape
and form, does not conduct electricity, is resistant to chemicals, heat insulating
and shatter-proof. Suggest possible uses for this material.
Handles of kitchen utensils / Electrical plugs / War weapons / Lightweight war machinery.

(Accept any other reasonable answers.)

5. The bar chart below shows the thermal conductivity of various metals, given the
scale 100 for the thermal conductivity of silver.

silver

copper

gold

aluminium

nickel

iron

tin

stainless
steel

20 40 60 80 100

a) In general, a material that has a high thermal conductivity also has a high
electrical conductivity.

i) Based on this statement, which metal is the best electrical

conductor?
Silver.

ii) Why then instead of using this metal (in (i)), copper is used in
wires? Suggest a possible answer.
Silver is more expensive than copper./ Silver is more difficult to obtain.

b) Metals are commonly used to make cookware and bakeware. Among the most
common metals used for this purpose are iron, aluminium and copper. Which
of these cookware — an iron pan, an aluminium pan or a copper pan — will
cook food most quickly? Why?
Copper. It is the best conductor of heat of the three; therefore, food can be heated more evenly.

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Classification of Matter 45

 Get It Right

Observe the design of the playground nearby your block.

a) Identify the material that makes the chin-up bar. Why do you think the chin-up bar
is made of this material?
The chin-up bar is made of steel. This is because steel is strong; it can support heavy load repeatedly

without breaking or tearing.

Study how a chin-up bar is used and refer to the Science Matters Textbook Volume
A, section 4.3 on Types of Materials.

b) The floor of the playground is layered with a soft, flexible, rubbery material.
Suggest two advantages of using this material.
The material is soft; hence, a kid will not get injured when falls onto it. The material is also flexible; it

will return to its original shape.

Recall the behaviour of a material that is soft and a material that is flexible. Refer to the
Science Matters Textbook Volume A, section 4.2 on Types of Physical Properties.

d) The slide is made of plastics. Suggest why it is not made of metal.

Metals conduct heat well. When the sun is shining, the slide will easily get heated up. No one will be
able

to play on the slide.

Study how slides are used and recall the properties of metals from the Science Matters
Textbook Volume A, section 4.3 on Types of Materials.
Name: Class: Date:

Chapter 5 Elements,
Compounds and
Mixtures
Worksheet 5.1 For Science Matters Textbook Volume A, sections:
5.1 What is Matter Made Up of? 5.3 Periodic Table
5.2 Classifying Elements

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. The following are matter except .

A sound B hydrogen
C cloud D air ( A )

2. Which of the following does not give the correct analogy of elements as building
blocks of matter?

A B

C D

( C )

3. Which of the following is not a pair of an element and its chemical symbol?
(You can refer to the Periodic Table.)
A Calcium — Ca B Carbon — C
C Chlorine — Cl D Copper — Co ( D )

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Elements, Compounds and Mixtures 1
4. In a Periodic Table,
Metals
a) are there more metals or non-metals?
A group
b) what do we call the elements found in the same vertical column?

c) describe one property that can help you differentiate between a metal and a
non-metal. Give an example using one metallic and one non-metallic elements.
Copper — malleable (can be bent and moulded into shapes); sulphur — brittle (breaks into pieces).

5. Graphite and diamond are two forms of the element carbon.

What is the property of these two substances that makes
graphite suitable for use in pencil lead and diamond in
cutting tools?
Graphite — soft and flakes off easily against surface.

Diamond — very hard substance.

5. The following elements are given.

sodium mercury phosphorus copper helium

chlorine tin cadmium fluorine tungsten

a) Briefly describe, by completing the graphic organiser below, how you can
identify whether an element is a metal or a non-metal using the Periodic Table.

Is the element located on the left

of the zigzag staircase line?

Yes No

A metal A non-metal

b) Using the steps in (a), classify the elements given into metals and non-metals.

Metals Non-metals
sodium mercury copper tin phosphorus
cadmium tungsten helium
chlorine
fluorine
Challenge Yourself • 20 min •

Attempt the following questions within the time allocated.

1. Marie read from a science book a statement

that says “the melting point of pure ice is 0 °C
whereas ice containing dissolved common
salt (sodium chloride) melts at −2 °C”. What
can we deduce from this statement?
A Pure ice is separated from sodium chloride at −2 °C.
B Sodium chloride in ice
forms a compound as it
has a different melting
point from pure ice.
C Sodium chloride melts at −2 °C.
D The melting point of impure ice is lower than that of
pure ice. ( D )

The following table shows the properties of

three unknown substances. Use the
information given in this table to answer
questions 2 – 3.

Effects of
Unknown passing Effects
substance electricity of
Appearance through the heati
unknown ng
substance in a the
circuit with a unkn
I light bulb own
subst
C The bulb lights
o ance
l up; a colourless
o gas and a brown
u
r gas are Boils
l produced. and
e
s produc
s es a
l
i colourl
q ess gas;
u
i a white
d precipi
tate is
formed.
bulb does not light
II Silvery solid The up.
bulb lights up.

III Yellow solid The

T o ngent gas.
u
r s
n t 2. Which substances are likely to be elements?
s i
c A I and II B I and III
i k C II and III D I, II and III
n y
t , 3. Which substance(s) could be used for making alloys?
o
A I y B II
s C III e D I and II ( B )
i l
l l
v o
e w
r i
y s
h
l
i o
q r
u a
i n
d g
e
a
t l
h i
i q
g u
h i
d
t ,
e
m t
p h
e e
r n
a
t p
u r
r o
e d
. u
c
T e
u s
r
n a
s
i p
n u
t
4. Explain the following:
a) Alloys of aluminium are used to make aircraft bodies instead of pure
aluminium.
Alloys are harder than pure elements of metals such as aluminium.

b) Objects made of iron are usually coated with paint or a layer of protective metal.
Iron can rust and corrode away if it comes into contact with oxygen. Paint and other protective

metals help to prevent rusting.

c) Electrical wires are usually made of copper.

Copper conducts electricity and is ductile (can be pulled into long wires without breaking).

5. The table below shows the properties of four elements, K, L, M and N.

Electrical Thermal Melting

Element Strength
conductivity conductivity point
K High Low Low Brittle
L High High High Strong
M Low Low Low Brittle
N High High Low Strong

a) Which element is definitely a metal? Give your reason.

Element L. It has all the properties that metals in general have: high electrical and thermal

conductivity, high melting point and strong.

b) Element N is also a metal.

i) How is element N different from the element in (a) at room temperature?
Element N is liquid at room temperature while element L is solid at room temperature.

ii) Suggest the identity of element N.

Mercury

iii) Give an example of the uses of element N in everyday life.

Liquid in thermometers
Name: Class: Date:

Worksheet 5.2 For Science Matters Textbook Volume A, section:

5.4 What are Componds?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following substances is a compound?

A Bronze B Gold
C Steel D Water ( D )

2. When a compound such as sugar is heated strongly, it .

A combines with oxygen in air B decomposes
C melts D undergoes combustion ( B )

3. Which of the following substances cannot be separated into two elements by

electricity?
A Aluminium oxide B Calcium chloride
C Sodium bromide D Titanium ( D )

4. Listed below are some of the ingredients shown on a carton of chocolate milk.

milk powder, sugar, cocoa powder, stabilisers, emulsifiers,

flavourings, calcium, vitamin C, vitamin E, vitamin B6, vitamin B1,
vitamin A, vitamin K and vitamin D3

a) Name the ingredient that is an element.

Calcium

b) How do you think the element in (a) is different from cocoa powder? Explain.
The element calcium cannot be broken down into any simpler substances. Cocoa powder, on the

other hand, can most likely be broken down into simpler substances. Cocoa powder is not found in

the Periodic Table. Those that are not in the Periodic Table may be compounds or mixtures.
Challenge Yourself • 10 min •

Attempt the following questions

within the time allocated.

1. When substances such as copper

carbonate and sugar are heated,
they are broken down into simpler
substances.

a) Write down the name of this

Decomposition
process.

b) What does this tell you about

these two substances? They are not
elements.

2. a) Write a word equation to

describe what happens when sugar is
burnt.
heat
Sugar Water + Carbon

b) Why does magnesium not

behave in a similar manner
when heated? What is formed
instead when magnesium is
burnt in air?
Magnesium is an element, so it cannot
be broken down into simpler
substances. Magnesium oxide

is formed.

3. Study the following diagram.

y
e
l
l
o
with
w
other
form
p
o
w
d
e
r
 Z
black solid
a
)
I
d
e
n
t
i
f
y

t
h
e

f
o
l
l
o
w
i
n
g
:

i) ii) Y:
X: Sulphur
Iron

b) How do you know

that a new substance is
formed from the reaction.
The product, iron

sulphide, does not have

the physical properties

of its constituent

elements. For example, it

does not have the

magnetic property of

iron.
Name: Class: Date:

Worksheet 5.3 For Science Matters Textbook Volume A, section:

5.5 What are Mixtures?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following lists of substances consists only of mixtures?

A Dust, sea water, milk, petroleum
B Ink, fizzy drinks, soil, distilled water
C Smoke, steel, blood, sugar
D Wine, paint, common salt, beer ( A )

2. When a mixture is formed, .

A a chemical change takes place
B heat and light are produced
C it has properties which are different from the properties of its
components
D the components are present in variable amounts ( D )

3. Classify the following into elements, mixtures and compounds.

bronze silver mercury wine

brass oxygen air milk
alcohol iodine sugar common salt
copper sulphate soya sauce carbon dioxide nitrogen

Elements Mixtures Compounds

Silver, mercury, Bronze, air, milk, Alcohol, sugar,

oxygen, iodine, soya sauce, brass, wine common salt,
nitrogen copper sulphate, carbon
dioxide

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Elements, Compounds and Mixtures 53
4.
wine air smoke copper brass sulphur
milk bronze magnesium zinc steel carbon

Select from the above list,

Air, smoke
a) two mixtures which exist as gases at room temperature:
Wine, milk
b) two liquid mixtures:

Brass, bronze, steel

c) three solid mixtures:

d) two non-metals: Carbon, sulphur

Map It Out

Complete the graphic organiser that follows the question below.

Using what you know about elements, compounds and mixtures, compare distilled
water and sea water.

Distilled water Sea water

Similarity
Both contain water.

Differences

It cannot be separated by It can be separated by

physical method. physical method.

It has properties which are It has properties which are

different similar to its constituent
from its

constituent elements . substances .

Constituents are combined Constituents need not

in fixed proportions. be mixed in any fixed
proportion.

Distilled water is a compound . Sea water is a mixture .

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Elements, Compounds and Mixtures 1
Challenge Yourself • 10 min •

Attempt the following questions within the time

allocated.

1. Marie adds a small piece of sodium to a beaker

of water. The sodium moves about quickly on
the surface of the water producing a hissing
sound. It gets smaller and smaller until it
disappears. The word equation for the reaction
that occurs is:

Sodium + Water → Sodium hydroxide + Hydrogen

a) What can you say about the density of sodium?

Explain your answer.
Sodium is less dense than water. It floats on the water surface.

b) Sodium is a metal. State one physical property of

sodium.
It is a good conductor of electricity.

c) A solution of sodium hydroxide is left at the

end of the reaction. State whether each of
the following is an element, compoud or
mixture.

i W

) a

S e

o r

d iii)

i Sodi

u um

m hydr

oxid

i e iv)

i Hyd

) roge

n
 v) Element r a ?
S co
Compound Air is a mixture.
ol mp
ut oun
io Compound d or b) Name at least
n a three constituents of
Element
of mix air?
so Mixture ture
Nitrogen, oxygen, carbon dioxide
di
u
m c)
h
y W
dr h
o a
xi t
de
i
s
2. The pie chart below
shows the composition of air. t
h
The e
1% of
air is m
78% mad
nitrogen i
e up n
of i
1% other
carb m
on u
dioxi m
21% de
oxygen gas p
and e
other r
subst c
ance e
s n
such t
as a
dust g
and e
micr
oorg o
anis f
ms.
a e
) l
e
I
m
s
e
n
a
t
i
s
99% (78% nitrogen
+ 21% oxygen)
 Get It Right

Observe the following illustration closely.

a) Why are light and shadow not considered matter?

Light and shadow do not have mass and do not occupy space.

Refer to the Science Matters Textbook Volume A, section 5.1 on What is Matter Made Up of?

b) The element carbon is found in the pieces of paper and in the pencil lead.
i) State the chemical symbol and the position of this element on the Periodic
Table.
Chemical symbol: C, position: Period 2, group IV

Refer to the Science Matters Textbook Volume A, section 5.3 on Periodic Table.

ii) If each, paper and pencil lead, is connected to a light bulb circuit, which one
will turn on the light bulb? Why?
When connected to the circuit, the pencil lead will turn on the light bulb. Carbon in the pencil lead

is in the form of graphite. Graphite conducts electricity.

Refer to the Science Matters Textbook Volume A, section 5.2 on Classifying Elements.

c) The metallic chair is a mixture. Suggest why this is so.

The metallic chair is an alloy. An alloy is a solid-solid mixture.

Refer to the Science Matters Textbook Volume A, section 5.5 on What are Mixtures?
Name: Class: Date:

Chapter 6 Separation of Mixtures

Worksheet 6.1 For Science Matters Textbook Volume A, sections:

6.1 Separating Mixtures 6.3 Filtration
6.2 Magnetic Attraction 6.4 Evaporation

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following shows the correct sequence to separate a mixture of salt
and pepper, and obtain dry samples of each?
I Adding water and stirring
II Evaporating to dryness
III Filtering the mixture
A I II III B I III II
C II III I D III I II ( B )

2. Which of the following cannot be separated from a waste metal junkyard by use of
magnetic attraction?
A Iron gate grills B Scrap iron doors from cars
C Steel utensils and cutlery D Zinc-plated roof tops ( D )

3.
Using the diagram on the left, explain why solid
particles can be separated from a liquid by
filtration.

The large particles of the solid are trapped on the

filter paper because they are too large to pass through

the pores/small holes on the filter paper.

4. Why is filtration of sea water unable to yield a pure filtrate? What are the impurities
found in the filtrate?
The filtrate contains dissolved substances that are able to pass through the small pores in the filter

paper. These substances include dissolved minerals, pollutants and dissolved gases.

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Separation of Mixtures 1

 Map It Out

Complete the graphic organiser that follows the question below.

Given a mixture of chalk powder and salt, describe how you can separate and obtain dry
portions of each substance.

Mixture of dissolves
Add water & stir Salt . Chalk powder
chalk powder
and salt is insoluble .

Filtration

Chalk powder is the Salt solution is the

residue. filtrate.

Evaporation to
Drying dryness

Dried chalk powder Salt crystals

Challenge Yourself • 5 min •

Attempt the following questions within the time allocated.

1. Geno wants to obtain iodine from a solution of iodine in ethanol. What would be a
suitable method?
A Chromatography B Distillation
C Evaporation to dryness D Filtration ( C )

2. Marie accidentally mixed tea leaves with salt. Suggest how Marie should separate
the mixture to obtain the tea leaves.
Add water into the mixture and stir the mixture. Then filter the mixture to obtain the tea leaves on the

filter paper. Air-dry the tea leaves.

Name: Class: Date:

Worksheet 6.2 For Science Matters Textbook Volume A, section:

6.5 Distillation

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. When we distill a mixture of salt water, the pure water is collected as the .
A distillate B filtrate
C pure substance D residue ( A )

2. Which of the following substance(s) is/are obtained by distillation?

I Wine from fermentation of grapes
II Petrol from crude oil
III Clean air
A I only B I and II only
C I and III only D All of the above ( B )

3. The processes in distillation involve .

A combustion then condensation B condensation then evaporation
C evaporation then condensation D filtration then condensation ( C )

4. The diagram on the left shows the apparatus

for distillation. A water
out
a) Label the following parts.
B
Thermometer
A:

B: Condenser
boiling
chips
C: Distillate water
in
b) What is the function of part B? C

To turn a vapour into a liquid for collection.

c) Why are boiling chips placed in the distilling flask?

To ensure smooth boiling.

d) Why is the direction of water into the condenser from the bottom?
To ensure maximum condensation of vapour in the condenser.
Challenge Yourself • 15 min •

Attempt the following questions

within the time allocated.

1. There is a change in the state of

matter in the following separation
methods except
.
A distillation
C filtration

2. Which of the following

is the difference between
filtrate and distillate?
A Filtrate is
obtained from
physical
separation,
whereas
distillate is
obtained from
chemical
separation.
B Distillate is a pure liquid,
whereas filtrate may not be a pure
liquid.
C Filtrate is a liquid, whereas
distillate is not a liquid.
D Distillate is obtained from
solid-solid mixture, whereas filtrate
is obtained from solid-liquid
mixture.
( B )

3. The diagram below shows the

fractionating column used to
separate fractions of petroleum.
20 °C petroleum gas

1
5 gasoline (petrol)
2
0 kerosene

crude oil
3 diesel
0
industrial fuel oil
3
7

4
0
 l
furnace
u
b c) Write down the order in which
r fractions are obtained in this
i
c
process.
a
t Petroleum gas, gasoline (petrol),
i
n kerosene, diesel, industrial fuel oil
g

o
and lubricating oil, paraffin wax and
i
l asphalt.
,

p
a
r
a
f
f
i
n

w
a
x

a
n
d

a
s
p
h
a
l
t

a) The fractions of
petroleum are
separated using a
method known as
fractional
distillation. Which
property of the
fractions makes this
method of
separation works?
Different boiling points of
the fractions.

b) Briefly explain how

the process takes place.
The fraction with the
lowest boiling point boils
first, hence it is obtained
as the distillate first. After

all this fraction distills, the

fraction with the second
lowest boiling point gets
distilled and so on.
Name: Class: Date:

Worksheet 6.3 For Science Matters Textbook Volume A, sections:

6.6 Paper Chromatography
6.7 Reverse Osmosis

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following processes allow you to obtain pure substances from the
mixtures?
I II III Evaporation
Distillation
Chromatography
AC I and II B I and
II and III D III III ( C )
only

2. Which of the following methods is used to obtain desalinated water in Singapore?

A Distillation B Evaporation to dryness
C Filtration D Reverse osmosis ( D )

3. Which separation process below does not correspond to its use?

Method Use
A Chromatography Separate traces of dyes from ink samples
B Distillation Test trace levels of drugs in urine samples
C Evaporation to dryness Obtain sea salt
D Filtration Separate tea leaves from tea ( B )

4. Complete the following table with the suitable method used to obtain each
substance from the mixture:

Substance to obtain Separation Method

Sand from sea water Filtration Evaporation
Sodium chloride from salt water to dryness Distillation
Alcohol from beer Chromatography
Permitted food dyes in sweets Filtration
Water after boiling barley seeds
5. A chromatography was carried out on unknown samples M1 and M2 and on three
known dyes X, Y and Z. The results are shown in the chromatogram below.

M1 M2 X Y Z M M2 X Y Z
1

Before After

a) What dyes are found in M2?

Dyes Y and Z.

b) If M1 is made up of dyes X and Z, draw the spots to show the results for M1
after chromatography is completed.

6. Outline how NEWater is obtained by reverse osmosis.

Sea water is pre-treated to remove debris and contaminants such as oil, grease and suspended solids. In

reverse osmosis, the pre-treated sea water is then pumped at high pressure through partially permeable

membranes to remove undesirable contaminants such as bacteria, viruses, most chemicals and dissolved

minerals.

7. How are the filter paper used in filtration and the partially permeable membrane
used in reverse osmosis similar?
Both filter paper and partially permeable membrane prevent certain particles to pass through.
Challenge Yourself • 10 min •

Attempt the following questions within the time allocated.

1. An ink sample on a forged cheque is

dissolved in ethanol. How do you obtain a
concentrated sample of the ink to run a
chromatogram?
A Heat the ink-ethanol mixture to
evaporate some of the ethanol away.
B Evaporate the ink-ethanol
mixture to dryness in an evaporating
dish. C Filter the ink-ethanol
mixture.
D Shake the ink-ethanol mixture in a separating funnel.
( A )

2. A small slip of paper stained with ink is

found at the scene of a crime. Why is
chromatography useful in analysing the ink?
Only small amounts are needed; it can separate the ink components to
determine the source/make-up of

the ink sample.

3. Study the table below, which shows the properties of three

substances.

Substance Effect of heat Adding wa

X Stable to heat Insolubl
Y Decomposes Dissolve
Z Sublimes Dissolve

Substances X, Y and Z are mixed. Starting from

the mixture, briefly describe how you would
obtain a dry sample of each of the following:

a) substance X
Add water to the mixture and stir to dissolve the soluble substances.
Filter the mixture and dry the

residue.

b) substance Z
Heat the mixture in an evaporating dish with

an inverted filter funnel placed above the dish.

C

oll

ec

su

bs

ta

nc

fo

rm

ed

on

th

all

of

th

in

ve

rte

fil

ter

fu

nn
 Get It Right

The Food and Drug Authority (FDA) examines various consumable products that are
going to be released to the market. For a generic cough syrup, for example, an FDA
chromatogram sets the standard for a safe-to-consume cough syrup.
Company X came with a new cough syrup product, Stop Cough. An FDA officer
conducted paper chromatography on the new product.

chromatogram of the chromatogram

generic cough syrup of Stop Cough

a) A substance with high solubility travels quickly along a chromatogram. Which

substance is most soluble on the chromatogram?
Substance at the highest position is most soluble.

b) Study the chromatogram of the product Stop Cough.

i) How is this chromatogram different from the chromatogram of the generic
cough syrup? Identify the different spot.
Spot R does not appear in the chromatogram of the generic cough syrup.

ii) What could be inferred from this result?

The product Stop Cough could contain one more substance than the generic cough syrup.

iii) Is the product Stop Cough safe for consumption? Why?

It may not be safe for consumption as the substance R may be harmful for the body.

Remember that different substances have different solubilities; hence, they travel
along the chromatography paper at different speeds.
Name: Class: Date:

Chapter 7 Solutions and

Suspensions

Worksheet 7.1 For Science Matters Textbook Volume A, sections:

7.1 What are Solutions?
7.2 What are Suspensions?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. Which of the following does not describe a solution?

A It contains the same amount of dissolved solute per cm3 of the mixture.
B It does not produce any residue when filtered.
C It has an insoluble solute in a solvent.
D No particles settle to the bottom when left to stand for a long time. ( C )

2. Which of the following is not a solution?

A Antiseptic iodine B Orange juice
C Eye drops D Mineral water ( B )

3. Which of the following set-ups is used to identify if a substance is a solution or a

suspension?
A B C D

( D )

4. C Talcum
Which of the powder
these substances forms aDsolution
Oil when added to water?

A Rock sugar B Chalk powder

( A )

©
© 2007
2008 Marshall
Marshall Cavendish
Cavendish International
International (Singapore)
(Singapore) Pte
Pte Ltd
Ltd Solutions and Suspensions 1
5. Classify the following into solutions and suspensions.

muddy water soya sauce vinegar wine

salad dressing perfume toothpaste antiseptic mouthwash

Solutions Suspensions
Soya sauce Muddy water
Vinegar Salad dressing
Wine Toothpaste
Perfume
Antiseptic mouthwash

6. Complete the following table.

Examples of
Type of solution Solute(s) Solvent
solution
Solid dissolves in Antiseptic iodine Iodine Alcohol
liquid
Salt water Salt Water
Liquid dissolves Beer, wine Alcohol Water
in liquid
Vinegar Ethanoic acid Water
Gas dissolves in Carbonated drinks Carbon dioxide Water
liquid
Pond water Oxygen, carbon dioxide Water

7. Dental amalgam has been used by dentists for over a century. It is used in tooth
filling and is a stable alloy containing silver, copper and tin dissolved in mercury.
It has been researched on and is durable, easy to use, highly resistant to wear and
tear and relatively inexpensive.

State which are the solutes and solvent in dental amalgam.

Solutes — silver, copper and tin

Solvent — mercury

dental amalgam
 Map It Out

Complete the graphic organiser that follows the question below.

Given a salt solution and a calamine lotion, explain how you can conduct tests to
observe the differences between the two substances.

Salt solution Calamine lotion

Differences

Homogeneous Non-homogeneous

When left to stand on its own, When left to stand on its own,
solute solid particles
the does not settle to the
bottom.
separate from the solvent

.When filtered, no residue is When filtered, a residue is

obtained. obtained.

Challenge Yourself • 25 min •

Attempt the following questions within the time allocated.

1. Which of the following actions would be useful to remove a non-water-soluble ink

stain from a shirt?
A Rub the stain with another solvent for ink.
B Soak the shirt for a longer time in water.
C Stir the shirt in water.
D Use hot water for washing the shirt. ( A )

2. The label on a bottle of liquid medicine says “Shake before use.”

a) Is the medicine a solution or a suspension? Explain.

A suspension. The suspended particles settle to the bottom of the bottle after some time. Shaking

allows the setting particles to disperse throughout the liquid.

b) What is the disadvantage of not shaking the bottle of liquid medicine before
taking it?
The dosage of certain substances in the medicine taken will not be correct, either too little or too

much. Medicine may work less effectively in the body.

3. The following diagram shows the stages (A to G) in water treatment.

A Here, a metal screen removes B Oxygen is dissolved in water

large objects such as twigs. to get rid of taste and
smell.

C Chemicals are added to

cause fine impurities to
reservoir clump together.

pump

screening aeration
tank system

filter tank coagulation tank

D Water is let
to stand.
E Water is filtered.

Chlorine is added to
F kill microorganisms.
sedimentation tank

prevent tooth decay.

clean water tank pump

storage reservoir home

a) i) List at least three stages that show that water from the reservoir is a
suspension.
A, C, D and E.

ii) Explain your answer in (i).

In A, large objects such as twigs are suspended in water. / In C, fine impurities clumping

together are suspended. / In D, lumps of impurities settle at the bottom of sedimentation tank.

In E, insoluble solid impurities are retained on the filtration bed.

b) Which stages of the water treatment show that water is a solvent? Name the
solute for each stage.
B, F and G. The solute in stage B is oxygen. The solute in stage F is chlorine and the solute in stage

G is fluoride.

c) Is water from the tap pure? Why?

No. It contains dissolved substances such as chlorine, fluoride and dissolved gases.
© 2007 Marshall Cavendish International (Singapore) Pte Ltd
Name: Class: Date:

Worksheet 7.2 For Science Matters Textbook Volume A, section:

7.3 What is Solubility? 7.4 What is Rate of Dissolving?

Secure Your Basics

Without referring to the textbook, try to answer these questions. If you cannot
answer a question, look up the relevant section in your textbook.

1. In which of the following will the greatest amount of sugar dissolve in 100 g of
water?
A Stirring sugar to a beaker of water at 80 oC
B Adding sugar to a beaker of water at room temperature
C Stirring sugar in a beaker of water at 40 oC
D Stirring sugar in a beaker of water at room temperature ( A )

2. Marie needs to prepare a saturated solution of the salt copper sulphate for her
experiment. What must she do before the solution becomes saturated?
A Continuously heat the mixture
B Grind copper sulphate before adding
C Keep adding copper sulphate and stir
D Keep adding water and stir ( C )

3. Which of the following actions would enable you to dissolve sugar faster to make a
syrup solution?
A Add more sugar. B Add more water.
C Heat up the water. D Use rock sugar. ( C )

4. a) State whether each of the following statements is true or false.

i) All substances are soluble in water. False

ii) Solubility of sugar increases with stirring. False

iii) Solubility is the amount of substance dissolved in 100 g of

solvent. False

iv) Powdered salt dissolves faster than rock salt in the

same solvent. True

v) Suspensions leave a residue after filtration. True

vi) A saturated salt solution remains saturated after heating. False

©
© 2007
2008 Marshall
Marshall Cavendish
Cavendish International
International (Singapore)
(Singapore) Pte
Pte Ltd
Ltd Solutions and Suspensions 69
 b) Explain your answer for each of the false statements in (a).
ii) Some substances, such as sand, are not soluble in water.

iii) The rate of dissolving of sugar increases with stirring. The solubility depends on nature of

solvent, nature of solute and the temperature.

iv) Solubility refers to the maximum amount of substance dissolved in 100 g of solvent at a

given temperature. (The amount of substance that is dissolved in 100 g of solvent is known

as concentration.)

vii) A saturated salt solution becomes unsaturated after heating. Saturation depends on temperature

— most substances become more soluble at higher temperatures.

5. Use the terms below to describe the underlined words or phrases in the following
statements.

solute solvent solution solubility

saturated rate of dissolving suspension

E.g. Sugar is added to water and stirred. Solute

a) Iodine is stirred in a test tube containing alcohol. Solvent

b) Calamine lotion contains insoluble solid particles in water. Suspension

c) The dissolved substances in sea water are the mineral

salts from rocks. Solute

d) We can design an experiment to determine the maximum

amount of sodium sulphate that can dissolve in 100 g
of water at room temperature. Solubility

e) Sally tries to find out how fast the sugar can dissolve
in water using a stopwatch. Rate of dissolving

f) Dissolved gas in water is known as a gas-liquid mixture. Solution

1 Solutions and Suspensions © 2008 Marshall Cavendish International (Singapore) Pte Ltd
6. The graphs below show the solubilities of some salts in 100 g of water against
temperature.

60

50

So
lu 40
bil
ity
(g/
10 30
0
g
of 20
w
at Key
er sodium sulphate
10 sodium chloride
ammonium sulphate

0
10 20 30 40 50
Temperature (°C)

a) Which substance is most soluble at 40 °C? Sodium sulphate

b) From the graph, infer the solubility of sodium sulphate at 35 °C.

46 g/100 g of water.

c) At about what temperature does ammonium sulphate become more soluble

than sodium chloride? 17 °C

d) Which substance shows the greatest change in solubility in response to the

change in temperature? Sodium sulphate

e) What can you infer from the graph of the solubility of sodium chloride with
respect to temperature?
The solubility of sodium chloride remains quite constant despite the change in temperature. / The

solubility of sodium chloride does not change much with temperature.

f) What can you infer from the graphs the solubilities of ammonium sulphate and
sodium chloride?
Solubility increases with temperature.

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Solutions and Suspensions 71
 7. Marie wanted to make iced lemon tea. She added freshly squeezed lemon juice to
ice water and added sugar crystals to sweeten the drink. However, the drink did not
taste sweet as the sugar did not dissolve completely.

What would you have done to sweeten the drink? Why?

Ice water has a low temperature; solubility of sugar is lowered. Sugar does not dissolve quickly. Add the

sugar to hot water and then add ice cubes to make the drink cold after that. We can also use sugar syrup

instead of sugar crystals.

Map It Out

Complete the graphic organiser that follows the question below.

The solubility and rate of dissolving of a solute depend on several factors. List some of
these factors.

Nature of Rate of
solvent Temperature stirring

Affecting Affecting rate

solubility of dissolving

Nature of Size of solute

solute
particles

1 Solutions and Suspensions © 2008 Marshall Cavendish International (Singapore) Pte Ltd
 Challenge Yourself • 20 min •

Attempt the following questions within the time allocated.

The table below shows the solubility of some salts. Use the information provided to
answer questions 1– 2.

Solubility
Salt
(g/100 g of water) at 20 °C
Sodium chloride 36
Potassium chloride 34
Copper chloride 73

1. At 20 °C, which of the following gives a saturated solution?

A 40 g of copper chloride dissolved in 50 g of water
B 20 g of potassium chloride dissolved in 100 g of water
C 35 g of sodium chloride dissolved in 100 g of water
D 72 g of sodium chloride dissolved in 250 g of water ( A )

2. What would be observed when a mixture of 20 g of sodium chloride stirred in 50 g of

water is filtered at 20 °C?
A A colourless filtrate is obtained and no residue remains.
B A colourless filtrate is obtained and white residue remains.
C A purple liquid is obtained.
D Only a white solid is obtained. ( B )

3. Isaac added a lot of iodine crystals into a test tube of alcohol and stirred it. Which
of the following does not help him conclude that he has a saturated solution?
I The mixture appears to be homogeneous.
II The mixture does not leave a residue after filtration.
III When more iodine is added, it cannot dissolve anymore.
A I and II B II and III
C I, II and III D III only ( A )

4. Most substances dissolve in greater amounts at higher temperatures. Which of the

following becomes less soluble at higher temperatures?
A Carbon dioxide B Iodine
C Sugar D Water-soluble ink ( A )

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Solutions and Suspensions 73
 5. A packet of jelly powder reads, “Pour contents of sachet into hot water”. Which
statement explains the instruction?
A The jelly powder becomes an unsaturated solution.
B The jelly powder forms a saturated solution at low temperature.
C The jelly powder is insoluble in cold water.
D The jelly powder takes a longer time to dissolve in cold water. ( D )

6. The label of a pack of coffee powder reads, “Pour hot water over coffee powder and
stir.” Based on your understanding of solubility and rate of dissolving, explain this
instructions.
Hot water — At higher temperatures, more coffee can dissolve at a higher rate.

Stirring — Stirring increases the rate of dissolving, so the drink can be prepared faster. The drink also

tastes better as more coffee has dissolved into the water, giving it a richer taste.

1 Solutions and Suspensions © 2008 Marshall Cavendish International (Singapore) Pte Ltd
 Get It Right

The table below shows the solubility of some substances at 20 °C.

Substance Solubility (g/100 g water)

Barium sulphate 0.00025
Sucrose 204.0
Baking soda 9.5
Sodium chloride 36.0
Calcium carbonate 0.0015

a) List the order of solubility of the substances in the table, starting with the least
soluble substance.
Barium sulphate, calcium carbonate, baking soda, sodium chloride, sucrose.

b) Determine the maximum amount of sucrose that can dissolve in 150 g of water at
20 °C.
204 g
× 150 g of water = 306 g of sucrose
100 g of water

Ask yourself, “If a maximum of 204 g of sucrose can dissolve in 100 g of water (see
table), how many grams of sucrose can dissolve in 150 g of water?” [Hint: Use
proportion.]

c) What do you expect to happen to the solubility of sodium chloride when the
temperature is increased to 40 °C?
The solubility should increase.

Refer to the Science Matters Textbook Volume A, section 7.3 on What is Solubility?

© 2008 Marshall Cavendish International (Singapore) Pte Ltd Solutions and Suspensions 75
 d) Marie stirred 6 g of baking soda in 50 g of water. What would she observe? Explain.
What do you call the resulting solution?
Some white baking soda remained undissolved; they settled at the bottom. The maximum amount of

baking soda that can dissolve in 50 g of water is 4.75 g. The resulting solution is called a saturated

solution.

Ask yourself, “How many grams of baking soda can dissolve in 50 g water if 100 g of
water can dissolve a maximum of 9.5 g of baking soda?” and “What will happen if
there is more baking soda?”

e) State the possible ways by which Marie can get all the baking soda to dissolve
Explain why you choose each method.
Heat the solution — solubility increases with temperature, hence more solute can dissolve at higher

temperatures.

Add more water — more solute can dissolve in a greater amount of solvent.

Explore the various factors that affect solubility and rate dissolving of a substance.
Refer to the Science Matters Textbook Volume A, section 7.3 on Solubility and section
7.4 on Rate of Dissolving.

1 Solutions and Suspensions © 2008 Marshall Cavendish International (Singapore) Pte Ltd