Transcript C1C2C3 01 Air pollution - Thomas Tallis Science Department

C1C2C3
02 Measuring air pollution
4
2
Scientists measure the concentration of particulates in the air in a town centre.
They do this on several days.
They also count the number of people seeking medical attention for asthma on the same days.
They plot their results on a scatter graph.
number
of people
seeking medical
attention
for asthma
concentration of particulates
(a) The data show a correlation.
Complete the sentence to describe this correlation.
As the concentration of particulates increases, the number of people seeking
medical attention for asthma
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(b) A journalist talks to the scientists about their data before it is published.
The journalist writes a newspaper article using the scientists’ data.
The article makes this claim.
‘Asthma is caused by particulates in the air’.
How much confidence can be placed in the newspaper claim?
The quality of written communication will be assessed in your answer.
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(c) Other scientists find a correlation between the sulfur dioxide concentration in the air and the
number of people seeking medical attention for asthma.
(i) Describe how sulfur dioxide can get into the air from motor vehicles and power stations.
...................................................................................................................................... [3]
(ii) Sulfur dioxide reacts with two chemicals in the air to form acid rain.
Which two chemicals?
Put a ring around each correct answer.
argon
carbon dioxide
hydrogen
nitrogen
oxygen
water
[2]
[Total: 12]
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2
Scientists investigated the nitrogen dioxide concentration in the air next to a city road over a
24-hour period on day 1.
Their results are shown in the graph.
300
250
200
nitrogen dioxide
concentration
in µg / m3
150
100
50
0
0
2
4
6
8
10
12
14
16
noon
18
20
22
24
midnight
time on day 1
(a) The World Health Organisation
concentrations.
(WHO) has set guideline limits for nitrogen dioxide
These are 200 µg / m3 for a one-hour average exposure and 40 µg / m3 for an annual average
exposure.
Look at the graph of measurements recorded on day 1.
(i) How many readings were above the one-hour average limit?
answer
[1]
(ii) How many readings were above the annual average limit?
answer
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(b) The scientists also counted the number of vehicles travelling along the road on day 1.
These results are shown in the tables.
Hour of
the day
1
2
3
4
5
6
7
8
9
10
11
12 noon
Number of
vehicles
2
3
5
9
31
54
242
461
584
472
287
277
Hour of the
day
13
14
15
16
17
18
19
20
21
22
23
Number of
vehicles
275
285
363
458
566
449
372
163
64
36
24
midnight
22
12
Use information from the tables to suggest an explanation for the shape of the graph.
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(c) The scientists repeated this investigation on day 2.
They measured the nitrogen dioxide concentration in four samples at the start of each hour.
The table shows the measurements they took at 9 am.
Sample number
1
2
3
4
Nitrogen dioxide
concentration
in µg / m3
286
284
285
281
(i) Use the measurements to work out the best estimate of the true value for the nitrogen
dioxide concentration at this time on day 2.
Show your working.
µg / m3 [2]
best estimate =
(ii) Look at the nitrogen dioxide concentration for 9 am on the graph for day 1.
Compare this with the value that you have calculated for day 2.
Suggest reasons for any difference between the two values.
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[Total: 9]
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2
Scientists measure the nitrogen dioxide concentration in the air next to a motorway.
They sample the air at nine different times.
At the same times they measure the number of vehicles per minute passing along the motorway.
Their results are shown in the graph.
concentration
of nitrogen dioxide
number of vehicles
per minute
(a) The graph shows the relationship between nitrogen dioxide pollution and the number of
vehicles per minute.
Use your knowledge of the reactions in a car engine to describe and explain this relationship.
The quality of written communication will be assessed in your answer.
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(b) At each time the scientists measure six samples of air.
They work out the mean value of these measurements.
The table shows the results from one set of six samples.
Sample number
1
2
3
4
5
6
mean
Nitrogen dioxide
concentration
in µg/m3
123
122
120
121
124
122
122
(i) Why is it an advantage to take six samples rather than one?
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(ii) The true value for the nitrogen dioxide concentration lies within a range of values.
According to the results in the table, what is this range?
range = from
to
µg/m3 [1]
(c) The scientists take measurements next to a different motorway.
Their results are different from those shown in the graph.
Suggest reasons for this difference.
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[Total: 12]
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