10
Living Science (Second Edition) Unit Test 2
Unit 10
Common acids and alkalis
S2 Science Test Common acids and alkalis
Name:____________________________
Time and Marks
Class: ____________________________
Part A: 35 min / 100 marks
Date: ____________________________
Parts Parts A & B: 45 min / 120 120 marks marks
Note: 1
Attempt ALL questions.
2
Write your answers in the spaces spaces provided on the Answer Answer Sheets.
Part Pa rt A (Lev (Level el 1) A
Matching
(4 marks, 1 mark each)
Which of the following substances contain(s) acids? Which of them contain(s) alkalis? Identify them by writing ‘acid’ or ‘alkali’ in the blanks on the answer sheets.
1
2
3
grape
B
soft drink
Multiple-choice questions
4
toilet cleanser
(20 marks, 2 marks each)
Choose the correct answer for each of the following questions.
1
2
Which of the following following plants can be used to make acidacid-alkali indicators? (1)
Red cabbage
(2)
Violet
(3)
Hibiscus
A
(1) and (2 (2) only
C
(2) and (3 (3) only
B
(1) and (3 (3) only
D
(1), (2) and (3 (3)
flower
Which of the following chemicals turn(s) red litmus paper blue? (1) Nitric acid
(2) Sodium chloride
(3) Ammo Ammonia nia
A
(2) only
C
(1) and (2 (2) only
B
(3) only
D
(2) and (3 (3) only
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glass cleanser
10
Living Science (Second Edition) Unit Test 2
3
4
5
Which of the following ways of using the pH meter are incorrect? (1)
Insert the probe directly into creamy skin lotion.
(2)
Rinse the probe with distilled water before use.
(3)
Insert the probe directly into the soil to measure the acidity of the soil.
A
(1) and (2) only
B
(1) and (3) only
C
(2) and (3) only
D
(1), (2) and (3)
Which of the following statements about the acidity / alkalinity of body fluids are correct? (1)
Different body fluids function normally even at changing pH levels.
(2)
Human blood has a normal pH of about 7.4.
(3)
Stomach juice is acidic while intestinal juice is alkaline.
A
(1) and (2) only
B
(1) and (3) only
C
(2) and (3) only
D
(1), (2) and (3)
Which of the following containers is not suitable for holding dilute hydrochloric acid?
A
B
Aluminium can
6
7
Common acids and alkalis
C
Glass bottle
Iron bucket
Below what pH value is rainwater defined as acid rain?
A
5.2
B
5.6
C
7.0
D
7.4
Which of the following chemicals is not a salt?
A
Sodium chloride
B
Sodium hydroxide
C
Potassium nitrate
D
Magnesium sulphate
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D
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Plastic cup
10
Living Science (Second Edition) Unit Test 2
8
9
Common acids and alkalis
Which of the following is the correct treatment for wasp stings?
A
Massage salt solution onto the wound.
B
Massage saliva onto the wound.
C
Massage baking soda onto the wound.
D
Massage vinegar onto the wound.
Which of the following is a fair test?
A
Add a drop of dilute sodium hydroxide and a drop of dilute hydrochloric acid onto a piece of white paper and a towel respectively. Compare their corrosive effects.
B
3
3
Put a piece of 5 mm-long iron ribbon and a piece of 10 mm-long magnesium ribbon into 5 cm and 10 cm of dilute hydrochloric acid respectively. Compare their rates of giving off gases.
C
Put three pieces of apple of the same size into each of the three solutions of the same volume but different acidities. Find what pH level preserves apples better.
D
Add a drop of diluted shower gel of one brand and another drop of undiluted shower gel of another brand onto pH papers. Compare their acidities.
10
C
Which of the following methods will increase the pH value of a solution?
A
Dilute concentrated sodium hydroxide solution.
B
Dissolve sodium chloride in distilled water.
C
Add dilute sodium hydroxide solution into dilute hydrochloric acid.
D
Add a drop of universal indicator into dilute nitric acid.
Fill in the blanks
(20 marks, 2 marks each)
Complete the following sentences.
1 2 3
Acids taste
c
and
a
b
while alkalis taste
d
.
are commonly used acid-alkali indicators in the laboratory.
The surface of aluminium reacts with oxygen in the air to form a layer of
e
which protects the aluminium
inside from further corrosion.
4
When dilute acids react with calcium carbonate,
5
Acids slow down the activities of most micro-organisms or even kill them, thus acids can be used for
6
When an acid and an alkali
7
One of the acidic air pollutants is
h
f
is given off.
each other, salt and water will be formed.
i
which dissolves in the rainwater to form sulphuric acid and makes
the rainwater more acidic.
8
Concentrated acids or alkalis give out
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g
j
on dilution.
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.
10
Living Science (Second Edition) Unit Test 2
D 1
Questions
Common acids and alkalis
(56 marks)
Mrs Wong is going to clean the marble surface with a bottle of acidic cleansing agent. Mr Wong stops her immediately.
a
Why can a cleansing agent containing acids or alkalis remove dirts and greases?
b
What would happen if Mrs Wong used the acidic cleansing agent to clean the marble surface?
c
(2 marks)
What gas would be produced?
(3 marks)
Suggest one way to test for the gas produced in b. Write down the expected observation.
(3 marks)
Mrs Wong is going to clean an iron can with the same bottle of acidic cleansing agent.
d
Should Mr Wong stop her this time? Why?
e
In the laboratory, adding iron ribbons into dilute acids will give off gas bubbles. What is the gas?
(2 marks)
Suggest one way to test for the gas. Write down the expected observation.
f
List one use of the acidic cleansing agent. List one safety precaution Mrs Wong should take when using this acidic cleansing agent.
2
(2 marks)
The figure on the right shows some plants probably destroyed by acid rain.
a
Explain briefly the formation of acid rain.
b
Why is the global acid rain problem getting worse in recent years?
c
Acid rain makes the soil acidic. How does it affect (2 marks)
Suggest one way to make the acidic soil suitable for the plants to grow.
e
(4 marks)
(3 marks)
the growth of plants?
d
(3 marks)
(2 marks)
Suggest two ways we can do to help prevent the formation of acid rain.
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(2 marks)
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10
Living Science (Second Edition) Unit Test 2
3
Common acids and alkalis
Mr Wong has got a stomach ache. The doctor diagnoses that it is caused by excess acid in his stomach.
a
What acid does the stomach juice contain?
(1 mark)
b
How does excess acid affect the stomach?
(2 marks)
c
The doctor prescribes a medicine for Mr Wong, claiming that the medicine can neutralize the excess acid in his stomach. What medicine is this? Why can it neutralize the excess acid in Mr Wong’s stomach?
d
(3 marks)
What substances are formed from the reaction of the medicine and the excess acid in the stomach?
e
(2 marks)
Jimmy said, ‘After neutralizing the excess acid with the medicine, the pH value of the stomach juice becomes 7.’ Do you agree with him? Why?
f
(3 marks)
Suggest two indicators commonly used in the laboratory for distinguishing acids from alkalis. For each indicator, write down the colour change when it is added to the stomach juice.
4
The figure on the right shows a bottle of concentrated household cleanser which should be diluted before use.
a
How dangerous is the concentrated cleanser when being used?
(2 marks)
b
Which hazardous warning label should be put on the bottle?
(1 mark)
c
Design an experiment to compare the corrosive effect of the cleanser with and without dilution.
(3 marks)
d
Describe the proper steps in diluting the concentrated cleanser.
(3 marks)
e
Suggest three safety precautions we should take when diluting the concentrated cleanser.
f
(3 marks)
Suggest one emergency treatment when the cleanser gets onto the skin.
(2 marks)
End of Part A
© Oxford University Press 2005
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(3 marks)
10
Living Science (Second Edition) Unit Test 2
Common acids and alkalis
Part B (Level 2) (20 marks) Mainland’s Acid Rain Affects Hong Kong Acid rain is a regional problem. Read the information about the acid rain problem in the mainland of China below and answer the questions.
In 2004, nearly 80% of the rain fell in Shenzhen (
) was acid rain. It is probably due to the
degrading air quality in the Pearl River Delta ( ). Hong Kong (especially the North New Territories) may be affected by the acid rain, depending on the wind direction, the air pollutant concentration and the distribution of the rainfalls in the nearby regions. Acid rain can diffuse into the soil and rocks and dissolve the poisonous metals inside. This affects the marine life and other animals including humans through the food chain. Guangdong and Hong Kong plan to issue daily air quality data for the Pearl River Delta, hoping that the regional air quality can be improved.
The Pearl River Delta
1
Why is the air pollution problem getting worse in the Pearl River Delta in recent years? Give two reasons.
(4 marks)
2
The acid rain problem faced by Shenzhen may also affect Hong Kong. Why? Give two reasons.
(4 marks)
3
a
b 4
According to the above information, what are the environmental problems associated with acid rain?
(3 marks)
Give one more environmental problem caused by acid rain besides those mentioned in a.
(1 mark)
Can the release of the air quality data for the delta region help reduce acid rain?Give reasons for your answer.
5
(4 marks)
Other than releasing air quality data, suggest methods to solve the acid rain problem in the Pearl River Delta.
(4 marks)
End of Part B
© Oxford University Press 2005
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10
Living Science (Second Edition) Unit Test 2
Unit 10
Name: __________________
Common acids and alkalis
S2 Science Test Common acids and alkalis Answer Sheets Class: ____________
Marks: __________________ Total: 100% (Part A) / 120% (Parts A & B ) Section A Total
Part A (Level 1) A
Do not write in this box
Matching (4 marks, 1 mark each)
1 __________ 2 __________ 3 __________ 4 __________ Section B Total
B
Multiple-choice questions (20 marks, 2 marks each)
Do not write in this box
1 __________ 2 __________ 3 __________ 4 __________ 5 __________ 6 __________ 7 __________ 8 __________ 9 __________ 10 __________
C
Fill in the blanks (20 marks, 2 marks each)
a ______________________
b ______________________
c ______________________
d ______________________
e ______________________
f ______________________
g ______________________
h ______________________
i ______________________
j ______________________
D
Questions (56 marks)
1 a ___________________________________________________________________________ ___________________________________________________________________________
b ___________________________________________________________________________ ___________________________________________________________________________
c ___________________________________________________________________________ ___________________________________________________________________________
d ___________________________________________________________________________ e ___________________________________________________________________________ ___________________________________________________________________________
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Section C Total
Do not write in this box
10
Living Science (Second Edition) Unit Test 2
f
Common acids and alkalis
___________________________________________________________________________ ___________________________________________________________________________
2 a ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
b ___________________________________________________________________________ ___________________________________________________________________________
c ___________________________________________________________________________ d ___________________________________________________________________________ e ___________________________________________________________________________ ___________________________________________________________________________
3 a ___________________________________________________________________________ b ___________________________________________________________________________ c ___________________________________________________________________________ d ___________________________________________________________________________ e ___________________________________________________________________________ ___________________________________________________________________________
f
___________________________________________________________________________ ___________________________________________________________________________
4 a ___________________________________________________________________________ ___________________________________________________________________________
b ___________________________________________________________________________ c ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
d ___________________________________________________________________________ ___________________________________________________________________________
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10
Living Science (Second Edition) Unit Test 2
Common acids and alkalis
e ___________________________________________________________________________
Section D Total
Do not write in this box
___________________________________________________________________________
f
___________________________________________________________________________
Part B (Level 2) (20 marks) 1 _______________________________________________________________________________ _______________________________________________________________________________
2 _______________________________________________________________________________ _______________________________________________________________________________
3 a ____________________________________________________________________________ ____________________________________________________________________________
b ____________________________________________________________________________ 4 _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________
5 _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________
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Part B Total
Do not write in this box
10
Living Science (Second Edition) Unit Test 2
Common acids and alkalis
S2 Science Test (Unit 10 Common acids and alk alis) Answers Part A (Level 1) A Matching (4%) 1 acid 2 acid 3 acid B
2B
C
3B
4C
5C
6B
7B
8D
9C
10 C
2 m each
Fill in the blanks (20%)
a sour f carbon dioxide D
b bitter g food preservation
c litmus / universal indicator h neutralize
d universal indicator / litmus i sulphur dioxide
e oxide j heat
2 m each
Questions (56%) a b
2
1 m each
Multiple-choice questions (20%)
1D
1
4 alkali
c d e f a
b c d e 3
a b c d e f
4
a b c d e f
The cleansing agent reacts with the dirts and greases so that the resulting substances can be wiped or washed away with water easily. 2m The acid would react with calcium carbonate in the marble. This would corrode the surface of the marble and make it rough. Carbon dioxide would be produced. 3m Use lime water. Carbon dioxide turns lime water from colourless to milky. 3m Yes, he should. This is because the acid is corrosive to iron. 2m The gas is hydrogen. Use a burning splint. If the gas is hydrogen, a ‘pop’ sound is heard. 3m Used to clean the toilet. Mrs Wong should wear a pair of plastic gloves. 2m Vehicles, power stations and factories release air pollutants such as sulphur dioxide and nitrogen oxides. 2m When these acidic gases dissolve in the rainwater, sulphuric acid and nitric acid are formed respectively. They make the rainwater more acidic. 2m 2m As industries develop and cities become densely populated, more fuels are burnt. 1m As a result, more sulphur dioxide and nitrogen oxides are produced. This makes the problem worse. Acid slows down the growth of plants. 2m Add lime to the acidic soil to raise the pH value at which the plants can grow well. 2m We can travel by public transport and switch off the electrical appliances when they are not in use. (or other reasonable answers) 1 m each The stomach juice contains hydrochloric acid. 1m Excess acid would damage the stomach wall, causing stomach ache and even stomach ulcer. 2m The medicine is antacid. Antacid is alkaline and thus can neutralize the excess acid. 3m Salt and water. 2m No. Because antacid only neutralizes the excess acid. Stomach juice works well only at an acidic environment. 3m Blue litmus. The stomach juice turns blue litmus red. 0.5 m each Universal indicator. The stomach juice turns the indicator from green to red. (It depends on the kind of indicator solution used in the laboratory.) 0.5 m each The concentrated cleanser is highly corrosive. The burn will be serious if our skin or eyes are in contact with it. 2m Corrosive. 1m Cut a piece of white paper into halves. Add a drop of concentrated cleanser and another drop of diluted cleanser 3m onto each piece. The cleanser which turns the paper yellow in shorter time is more corrosive. Pour water into a plastic basin to about half -full. Slowly pour the right amount of concentrated cleanser into water. Gently stir the mixture in the basin with a towel. 3m Wear a pair of plastic gloves. / Carry out the dilution in a ventilated area. / Continuously stir the solution. / 1 m each Slowly add the concentrated cleanser to a large amount of water. (any 3) Wash the affected area under slow running water for at least 10 minutes. / Gently remove any 2m contaminated clothing. (any 1 or other reasonable answers)
Part B (Level 2) (20%) 1 2 3 4 5
The fast development of industries in recent years increases the emissions of air pollutants. Moreover, more air pollutants are released from the increased number of cars. Air pollutants in Shenzhen may be blown to Hong Kong by wind. Rivers in the North New Territories may be polluted by the acid rain. a Affects the marine life and other animals including humans. 3 m b Corrodes stone and metal structures. Answers vary with students. (Control the emissions of air pollutants from factories and cars based on the data.) Answers vary with students. (Educate the public to travel by public transport. / Explore new energy sources.)
© Oxford University Press 2005
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4m 4m 1m 4m 4m