Part I
Planet Earth
Part I
Planet Earth
Our planet Earth provides us with plenty of natural
resources.
Chapter 1
Fundamentals of Chemistry
Chapter 2
The atmosphere
Chapter 3
The ocean
Chapter 4
Rocks and minerals
Chapter
1
Fundamentals of Chemistry
1.1 What is Chemistry about?
1.2 How is Chemistry related to daily life?
1.3 Observations, analyses and interpretations in Chemistry
1.4 Laboratory safety
1.5 Common apparatus in the chemistry laboratory
Learning goal
After studying this chapter, you should be able to:
1.1
• recognize what matter is and what Chemistry is about
1.2
• understand the importance of Chemistry to daily life
1.3
• recognize the importance of making observations in studying Chemistry
• realize the necessary steps in drawing conclusions from experiments
1.4
• state the basic laboratory safety rules
• know what hazardous chemicals are
1.5
• recognize the use of common laboratory apparatus
• draw vertical section diagrams of common laboratory apparatus
Chapter
1
Fundamentals of Chemistry
Hong Kong is one of the most densely populated cities in the world. In recent years, light pollution
problems have aroused the government’s concern.
An urban scene of Hong Kong where light pollution problems are serious.
In 2010, some Taiwanese researchers had an idea of replacing streetlights with trees. They found
that placing gold nanoparticles within the tree leaves would cause the leaves to give off red light.
Hence, the road could be lightened without the need of electricity. Besides, the light given off is softer
and far less polluting than traditional light bulbs and even LEDs.
The study of new materials like gold nanoparticles is a branch in Chemistry. Chemistry plays an
important role in changing the world we live in.
Think about...
What is Chemistry?
Chemistry is the study of substances, including their compositions, structures, properties and the changes among them.
Why is Chemistry important to us?
Many new substances can be made by applying the knowledge of Chemistry. Hence, Chemistry helps provide us with a good standard of living
What are the basic skills required for studying Chemistry? and is important for our survival.
We have to observe carefully and fully when doing experiment, report experimental results clearly and accurately, analyse the results and
try to interpret them, draw conclusions for the experiment.
After studying this chapter, you should be able to answer the above questions.
light pollution 光污染
nanoparticle 納米粒子
1 Fundamentals of chemistry
1.1 What is Chemistry about?
PowerPoint
What is matter?
The world around us is made up of matter. Matter is anything that
occupies space and has mass. One particular type of matter is called
substance. Iron, water and air are examples of substances.
What is Chemistry?
Chemistry is the study of substances, including their compositions,
Note 1
Structures of substances will be
further discussed in chapter 9 of
Book 1.
structures, properties and the changes among them. Chemists always N1
ask questions about the substances they study.
For example, chemists would ask the following questions about water:
1.How do the hydrogen particle and oxygen particle combine to
give a water particle?
2.What are the structures of water at different states?
3. What are the properties of water?
4.Why does water have different properties when compared with
hydrogen and oxygen?
5.Can we change water into other substances?
Key point
Chemistry is the study of substances, including their compositions,
structures, properties and the changes among them.
S
XTRA
E
Historical note
Chemistry and alchemy
The word chemistry comes from the word ‘alchemy’. During the Middle
Ages (about AD 500–1500), some people, known as alchemists, tried to
turn some cheap metals like iron or lead into gold. They tried to do that
by mixing and heating the metals with different substances together.
Although they did not succeed at last, the properties of many
substances became known during the process. Besides, various chemical
methods and laboratory techniques were developed. The efforts and
hard work of alchemists helped greatly in the development of Chemistry. Alchemists at work.
change 變化
Chemistry 化學
composition 成分
matter 物質
property 性質
structure 結構
substance 物質
alchemist 煉金術士
alchemy 煉金術
3 1
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1.2 How is Chemistry related to daily
PowerPoint
life?
Many inventions in Chemistry were made, one after the other, starting in
th
the 20 century. These inventions play an essential role in many parts of
our daily life, for example, clothing, food, housing, transport and medical
care. See Figure 1.1.
Food
Clothing
Food additives help improve the
taste, colour and freshness of food.
Synthetic fibres are N2
products of the
petrochemical industry.
They are very popular in
making clothes.
Note 2
Nylon and polyesters are
commonly used synthetic
fibres in textile.
(a) Synthetic fibres are used
in making clothes.
(b) Food additives are commonly
used in food production.
Transport
Housing
Building houses requires cement, steel, glass,
plastics, paints, etc. All of them come from the
chemical industry.
Modern transport like cars, aeroplanes and
ships requires fuels that come from the N3
petroleum industry.
(c) Many different construction materials
are needed for building houses.
(d) The fuel used by an aeroplane comes
from the refining of petroleum.
Medical care
Note 3
The common fuels for modern transport include
petrol, kerosene, diesel oil and fuel oil. They are
obtained from refining of petroleum.
Humans fight diseases
with drugs. Drugs are
chemical products. N4
Note 4
The active ingredient of aspirin is acetylsalicylic
acid with the formula of C9H8O4.
(e) Drugs for fighting diseases are
chemical products.
1
4
Figure 1.1 Chemistry is closely
related to daily life.
cement 水泥
chemical industry 化學工業
essential 必不可少的
food additive 食品添加劑
petrochemical industry 石油化學工業
petroleum industry 石油工業
steel 鋼
synthetic fibre 合成纖維
1 Fundamentals of chemistry
We can see that Chemistry helps provide us with a good standard of
living. Chemistry is not just a subject studied in school, but is also closely
related to other branches of science, technology and society.
Class practice 1.1
N5
The photograph below shows some items commonly found in the kitchen.
Which one(s) do you think is/are related to Chemistry? Circle them out.
Note 5
1. Fertilizers provide important nutrients to
enhance plant and fruit growth.
Insecticides help reduce the amount of
plants destroyed by pests.
2. Window frames are made of anodized
aluminium.
3. Tap water is sterilized by chlorine.
4. Detergents improve the cleansing ability
of water.
5. The outer layer of plastic gloves in the
picture is made of latex.
6. Town gas is produced from naphtha,
which comes from the petroleum industry.
7. Preservatives increase the shelf life of
instant cup noodles.
8. Baking powder is used in making bread.
9. Food container in the picture is made of
polypropene.
10. Food wrap is made of low-density
polyethene.
11. The bowl and dish in the picture are made
of ceramic and zirconium dioxide (ZrO2).
12. etc.
2
A1.1
1
6
4
3
5
1
11
7
8
10
9
1.3 Observations, analyses and
PowerPoint
interpretations in Chemistry
Observations in Chemistry
Learning tip
Tasting with the
tongue is also one
way of observation,
but it is NOT allowed
in the laboratory.
observation 觀察
Since Chemistry is a science based on experiments, observations are very
important. Observations in Chemistry involve the uses of our senses:
•
Seeing with eyes
•
Feeling with hands
•
Smelling with nose
•
Hearing with ears
5 1
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Note 6
Observations:
1. There is a flame with the shape of a water drop.
To be a good observer, we must be patient. We must try to notice even
small details or changes in an experiment.
2. The flame is hot.
3. The flame gives out light (i.e. a luminous flame).
Consider a burning candle (Figure 1.2). Write down as many
observations as you can make within five minutes.
4. The colour of the main part of the flame is yellow.
5. The flame is less bright at the lower part, i.e. near the wick. This part of the flame is less luminous.
Compare your observations with those of your classmates. Did you
make the same observations? How many different observations did the
whole class make? Check your observations against those suggested by
Figure 1.2
How many
things can you notice about
a burning candle? N6
H20
Example 1.1
your teacher.
6. The lowest part of the flame has a blue rim.
7. The flame is wavy even when there is no wind.
8. The tip of the flame is often irregular in shape (not having a smooth, sharp tip).
9. There is a stream of black smoke rising from the tip of the flame.
10. The wick turns black.
11. The tip of the wick occasionally gives a red glow.
12. The wick slowly shortens.
13. The wax directly under the flame melts to a liquid.
14. The wax is consumed during the burning of the candle.
Making observations
3
Add an effervescent vitamin C tablet to a glass containing 200 cm of water (Figure 1.3). Record your
15. If listened very carefully, the hot molten wax right below the flame may give a faint hissing sound.
observations.
16. Some of the molten wax may flow down along the shank of the candle.
17. The molten wax flowing down the shank of the candle soon becomes viscous and then solidifies again.
18. etc.
Solution
(1) There is effervescence — colourless gas
bubbles evolve from the tablet. (sight) N7
(2) The tablet gradually becomes smaller in size
and eventually dissolves completely to form a
colourless solution. (sight) N8
(3) The glass becomes cold. (touching)
(4) A pleasant smell is detected. (smelling)
(5) A hissing sound is heard. (hearing)
Figure 1.3 Adding a vitamin C tablet to water.
Note 7
Some students have the misconception that they need not mention the colour of a substance if it is colourless or white.
Another misconception is that when no observable change is noticed, ‘no reaction’ is written as answer. However, ‘no observable change’ does
NOT mean ‘no reaction’.
Experiment 1.1
PowerPoint
Experiment
Video
Experiment Workbook 1
Recording the observations of chemical reactions
In this experiment, you are going to record the observations of some chemical
reactions.
Note 8
This question asks for observations. Thus, it is wrong to write ‘Carbon dioxide evolves from the tablet.’. Further test is needed to identify the gas
evolved.
1
6
effervescence 泡騰/起泡
vitamin C 丙種維生素
evolve 釋出
hissing sound「嘶嘶」聲
patient 有耐性的
1 Fundamentals of chemistry
Analyses and interpretations in Chemistry
During an experiment, other than making observations, we should also
record the experimental results carefully and fully. Then we should
analyse the experimental results and try to interpret (explain) them.
Finally, we should draw conclusions for the experiment.
For all experiments we will do, we should try our best to:
Key point
(1) observe and record the experimental results carefully and fully.
(2) analyse the experimental results and interpret them.
(3) draw conclusions for the experiment.
1.4 Laboratory safety
PowerPoint
In this course, we often do experiments in the laboratory. To avoid
accidents, always remember: ‘Laboratory safety is of first importance
in any experimental work.’ (Figure 1.4).
Figure 1.4 Posters on laboratory safety.
laboratory safety 實驗室安全
analyse 分析
interpret 詮釋
7 1
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For example, never heat strongly when only gentle heating is required; never use concentrated acid/alkali when only a dilute one
is needed; never use excessive amounts of chemicals; never do any experiment not allowed/instructed by teachers.
Basic laboratory safety rules
Learning tip
For more details on the
safety precautions in
the Chemistry
laboratory, refer to the
‘Laboratory Handbook’.
We must follow all the basic laboratory safety rules when doing
Note 10
experiments. In case students are working in groups, it is a good practice to appoint a group leader, by
A1.2
• Student A should not run in the
laboratory as she may knock on the
other students who are doing
experiments and cause accidents.
Besides, she should wear safety
spectacles.
• Student B should not smell the gas
directly as the gas may be poisonous.
• Student C should wear safety
spectacles when doing experiment as
the chemical may spill into her eyes. In
addition, the flammable chemical should
not be placed near the flame as it
catches fire easily.
• Student E should not throw rubbish into
the sink as the solid waste may block
the drain of the sink. In addition, he
should wear safety spectacles.
• Student F should not touch the hot
beaker with bare hands as she would
get heat burns.
• Student G should not eat in the
laboratory as the food and drinks may
be contaminated with chemicals.
Besides, he should wear safety
spectacles.
rotation each time. He/she is the only person allowed to get and return apparatus and
chemicals. In so doing, ‘movement’ in the laboratory can be minimized.
Laboratory Safety Rules
(1)
Do not work in the laboratory unless your teacher is present.
(2)
Follow strictly the instructions given by your teacher. N9
(3)
ever run around or play in the laboratory. Do not leave your bench
N
unless it is necessary. N10
(4)
Do not touch any chemicals with bare hands.
(5)
Dispose of solid waste (e.g. broken glass, filter paper, copper turnings,
etc.) in the waste bin, never in the sink.
(6)
Clean up all the spillage (on the floor or bench) at once. Clean up the
bench after experiment.
(7)
Report all accidents and breakages to your teacher at once.
(8)
In case any chemical gets into eyes, flush the eyes with running water
immediately for at least three minutes.
(9)
For chemical burns on skin, place the affected area under slowly running
Note 11
water until the pain fades. N11
Remind students that the only reliable
(10) Take all necessary safety precautions. immediate treatment for all chemical burns
is washing with a lot of water.
Class practice 1.2
Study the following picture. Some of the students in the laboratory have improper actions against the laboratory
safety rules. Point them out and explain your answers.
D
C
B
A
G
E
1
8
safety precaution 安全措施
F
burn 灼傷
spillage 濺出/溢出
1 Fundamentals of chemistry
Hazardous chemicals CE2005(II)18
Note 12
Some household substances may
have potential risks. Take the
example of bleaching solution. It
liberates toxic chlorine gas when
mixed with acidic substance.
Hazardous chemicals are substances which may cause injury to people or N12
damage to property. Chemicals can be classified according to their
hazardous nature. A bottle containing a hazardous chemical should display
the appropriate hazard warning label(s). Figure 1.5 shows some common
hazard warning labels.
Figure 1.5 Some examples of common hazard warning labels.
Figure 1.6 A hazard warning label
(corrosive) is shown on a bottle of
concentrated hydrochloric acid.
1.5 Common apparatus in the chemistry
PowerPoint
laboratory
Common laboratory apparatus
We use many different pieces of apparatus when doing experiments in the
laboratory. Figures 1.7–1.13 show some common laboratory apparatus.
(b)
(a)
(d)
(a)
(c)
(b)
(d)
(e)
(c)
(h)
(e)
Figure 1.7
(a) Test tube rack
(b) Rubber stopper
(c) Test tube
(d) Boiling tube
dropping bottle 滴瓶
filter funnel 漏斗
hazard warning label 危險警告標籤
hazardous chemical 危險化學品
(g)
(f)
(f)
(h)
(e) Test tube holder
(f) Test tube brush
(g) Dropping bottle
(h) Reagent bottle
laboratory apparatus 實驗室儀器
measuring cylinder 量筒
reagent bottle 試劑瓶
(g)
Figure 1.8
(a) Measuring cylinder
(b) Beaker
(c) Dropper
(d) Filter funnel
damage 破壞
injury 傷害
(e) Wash bottle
(f) Watch glass
(g) Thermometer
(h) Glass rod
nature 性質
property 財產
9 1
I Planet Earth
(a)
(b)
(d)
(c)
(b)
(a)
(c)
(e)
(d)
(g)
(f)
(h)
Figure 1.9
(a) Stand and clamp
(b) Round-bottomed flask
Figure 1.10
(a) Crucible (with lid)
(b) Pipe-clay triangle
(c) Tripod
(d) Bunsen burner
(c) Flat-bottomed flask
(d) Conical flask
(e) Evaporating dish
(f) Heat-resistant mat
(g) Crucible tongs
(h) Wire gauze
(a)
(a)
(b)
(b)
(c)
(d)
(c)
Figure 1.11
(a) Desiccator
(b) Gas jar
Figure 1.12
(a) Weighing bottle
(b) Electronic balance
(c) Spatula
(c) Mortar
(d) Pestle
Figure 1.13 Safety spectacles
Some chemistry experiments can be done on a reduced scale. These
experiments are microscale experiments in which microscale apparatus
are used. See Figure 1.14. One major advantage of microscale experiments
is to save the amounts of chemicals used. N13
Note 13
Some advantages of microscale experiments:
1. The amounts of chemicals used and hence
the costs for chemicals can be reduced.
2. Reduce the wastage of chemicals.
3. Experiments can be completed in a shorter
period of time.
4. Reduce the space for storing the apparatus.
8-well reaction strip
microsyringe
micro-tip plastic
pipette
Figure 1.14 Microscale apparatus
1
10
8-well reaction strip 八孔井穴條
conical flask 錐形瓶
crucible tongs 坩堝鉗
desiccator 乾燥器
heat-resistant mat 耐熱墊
microscale experiment 微型實驗
microsyringe 微量調節注射器
micro-tip plastic pipette 微端塑膠移液管
mortar 研缽
pestle 研棒
pipe-clay triangle 管土三角
spatula 刮勺
tripod 三腳架
weighing bottle 稱量瓶
wire gauze 鐵絲網
1 Fundamentals of chemistry
Vertical section diagrams of common laboratory
apparatus
For convenience, we usually use simple diagrams to represent laboratory
apparatus and experimental set-ups in chemistry experiments. These
diagrams must be clear and easy to understand.
We can draw vertical section diagrams to represent laboratory
apparatus. The vertical section diagrams in fact represent the side-on
view of the apparatus. Some examples are shown in Table 1.1.
Beaker
Test
tube
Conical
flask
Filter
funnel
Table 1.1
Vertical section
diagrams of some common
laboratory apparatus.
vertical section diagram 縱切面圖
11 1
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Skill corner 1.1
Drawing vertical section diagrams of common laboratory apparatus
When we draw the vertical section diagram of a piece of laboratory apparatus, we should:
1. Find out the vertical section of the apparatus. Try to imagine as if a plane cut through the apparatus
into two halves from top to bottom.
For example, we can draw the vertical section diagram of a measuring cylinder as shown below:
2.
Note the following points:
• Draw the diagram with simple lines.
• Draw straight lines with a ruler.
•
•
Do not shade the diagram.
Do not add graduation marks, if any, on the side of the apparatus.
Class practice 1.3
For each of the following laboratory apparatus, write its name and draw a vertical section diagram that
represents it. A1.3
Apparatus
Name and vertical
section diagram
Apparatus
Test tube
(a)
Name and vertical
section diagram
Conical flask
(b)
(Cont’d)
1
12
graduation 刻度
shade 把…塗暗
1 Fundamentals of chemistry
Apparatus
Name and vertical
section diagram
Apparatus
Glass rod
(c)
Dropper
(d)
Tripod
(e)
Wire gauze
(f)
Evaporating dish
(g)
Name and vertical
section diagram
Watch glass
(h)
13 1
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Key terms
PowerPoint
English term
Chinese translation
Page
1.
Chemistry
化學
3
2.
hazard warning label
危險警告標籤
9
3.
hazardous chemical
危險化學品
9
4.
laboratory apparatus
實驗室儀器
9
5.
laboratory safety
實驗室安全
7
6.
matter/substance
物質
3
7.
microscale experiment
微型實驗
10
8.
observation
觀察
5
9.
safety precaution
安全措施
8
Progress check
PowerPoint
Can you answer the following questions? Put a ‘✓’ in the box if you can. Otherwise, review the relevant
part on the page as shown.
Page
1
14
1.
What is matter?
3
2.
What is Chemistry?
3
3.
How is Chemistry related to daily life?
4
4.
How can we make observations during an experiment?
5
5.
What are the necessary steps for drawing conclusions from experiments?
7
6.
What are the basic laboratory safety rules when doing experiments?
8
7.
What are hazardous chemicals?
9
8.
How can we draw vertical section diagrams of common laboratory apparatus?
11
1 Fundamentals of chemistry
Summary
PowerPoint
1.1
What is Chemistry about?
1.
Chemistry is the study of substances, including their compositions, structures, properties and
the changes among them.
1.2
How is Chemistry related to daily life?
2.
Chemistry plays an essential role in clothing, food, housing, transport and medical care.
1.3
Observations, analyses and interpretations in Chemistry
3.
Observations in Chemistry involve four senses:
4.
•
Seeing with eyes
•
Feeling with hands
•
Smelling with nose
•
Hearing with ears
For all experiments we do, we should try our best to:
(1) observe and record the experimental results carefully and fully.
(2) report the experimental results clearly and accurately.
(3) analyse the results and interpret them. Then draw conclusions and make predictions.
1.4
Laboratory safety
5.
Laboratory safety is of first importance in any experimental work. Refer to p.8 for basic
laboratory safety rules.
6.
Hazardous chemicals are substances which may cause injury to people or damage to property.
7.
azard warning labels are displayed on bottles containing hazardous chemicals. These
H
chemicals must be handled with great care.
1.5
Common apparatus in the chemistry laboratory
8.
Some common laboratory apparatus are shown in Figures 1.7–1.13 on p.9–10.
9.
For convenience, vertical section diagrams are usually drawn to represent laboratory apparatus
and experimental set-ups.
15 1
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Concept map
PowerPoint
Complete the following concept map.
Science
Importance to daily life:
• clothing
• food
• housing
• transport
• medical care
a branch of
CHEMISTRY
study of substances
Structures
Compositions
Properties
studied by
Experiments
make
and record
Observations
need the
use of
Laboratory
apparatus
need to
consider
Laboratory safety
(Hints: compositions, experiments, observations, properties, science, structures)
1
16
Changes
1 Fundamentals of chemistry
Chapter exercise
Fill in the blanks
Section 1.3
6.
Section 1.1
1.
The
world
matter
occupies
2.
around us is made up of
, which is anything that
space
mass
and has
.
Chemistry is the study of
compositions
including their
changes
properties and the
Section 1.3
3.
A. The water becomes white.
B. Colourless gas bubbles evolve from the
surface of sugar.
C. The sugar dissolves.
C
D. The glass becomes cold.
substances
,
, structures,
among them.
Section 1.4
7.
Observations in Chemistry include:
•
seeing with eyes;
•
feeling
with hands;
•
smelling
with nose;
•
hearing
with ears.
A.
B.
C.
D.
To do experiments safely in the laboratory, we
laboratory safety rules
should follow all the
.
Multiple-choice questions
8.
Section 1.2
5.
Which of the following
Chemistry are correct?
statements
about
(1) Chemistry is the study of various substances.
(2) Chemistry is a branch of science.
(3) Chemistry helps provide us with a good
standard of living.
A.
B.
C.
D.
(1) and (2) only
(1) and (3) only
(2) and (3) only
(1), (2) and (3)
If your finger is accidentally cut by a broken test
tube in the laboratory, you should
(1) report to the teacher at once.
(2) clean up the broken glass pieces with a towel.
Then dispose of the glass pieces in a rubbish
bin.
(3) clean the wound with water and then apply a
dressing to it. 7. Broken glass pieces should be cleaned
Section 1.4
4.
What will be observed if a spoonful of sugar is
added to a glass of water?
D
up with a broom and the glass pieces
should be disposed of in a waste bin
which is used for collecting broken
glass.
C
Which of the following hazard warning labels
should be shown on a gas jar containing
hydrogen?
A.
B.
C.
D.
9.
(1) only
(2) only
(1) and (3) only
(2) and (3) only
Corrosive
Explosive
Flammable
Toxic
8. Hydrogen is flammable.
C
Which of the following hazard warning labels
should be shown on the reagent bottle containing
concentrated hydrochloric acid?
A.
C.
B.
D.
5. Refer to p.3 to 5 of chapter 1 for details.
D
9. Concentrated hydrochloric acid is corrosive.
17 1
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Structured questions
Section 1.4
10. Cathy heated a test tube containing ethanol in the laboratory as shown below.
10. Any FIVE:
She did not stopper the reagent bottles
after taking the chemicals out from them.
She did not tie up her long hair.
She did not wear safety spectacles (and
laboratory coat).
She should NOT have heated the ethanol
directly as ethanol is flammable.
She should not have pointed the test tube
to herself.
She should not have placed the bottle of
ethanol near the Bunsen flame as ethanol
is flammable.
11. (a)
IRRITANT
⏉䅏ㆶ
(b) Wear safety spectacles.
Avoid contact with the eyes and skin; when
accidentally spilt into the eyes or onto the
skin, wash the affected area with a lot of
water.
(c) Colourless gas bubbles evolve from the
egg shell pieces.
The egg shell pieces dissolve in the acid.
ethanol
Cathy made FIVE mistakes when conducting the experiment. List them out.
11. Peter wants to find the amount of calcium in an egg shell. In the experiment, the egg shell is first ground
into smaller pieces by using a mortar and a pestle. Then, a known amount of dilute hydrochloric acid is added
to the egg shell. Dilute hydrochloric acid is irritant and should be handled with care.
(a) Draw the hazard warning label that should be shown on a bottle of dilute hydrochloric acid.
(b) Suggest TWO safety precautions when handling dilute hydrochloric acid in the laboratory.
(c) State TWO observations when dilute hydrochloric acid is added to the egg shell pieces.
Section 1.5
12. Below are some pieces of apparatus commonly used in the laboratory.
A.
B.
C.
D.
E.
F.
G.
H.
12. (a) A.
B.
C.
D.
(a) Name the pieces of apparatus A to H.
Beaker
Test tube/boiling tube
Bunsen burner
Wire gauze
E.
F.
G.
H.
Tripod
Heat-resistant mat
Test tube holder
Spatula
(b) Which piece(s) of apparatus would you use for each of the following purposes?
(i)
Transferring a small amount of solid sodium chloride from the reagent bottle to a test tube.
3
(ii) Studying the reaction between a few cm of dilute hydrochloric acid and an iron nail.
3
(iii) Heating a few cm of water.
3
(iv) Boiling 200 cm of water.
1
18
(b) (i) H
(ii) B
(iii) B, C, F, G
(iv) A, C, D, E, F