1. C1C2C3 02 Measuring air pollution

2. 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[1] C123 Jan 2012

3. 5 (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............................................................................................................................................... [6] (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. argoncarbon dioxidehydrogennitrogenoxygenwater [2] [Total: 12] Turn over C123 Jan 2012

4. 4 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 concentration150 in µg / m 3 100 50 0 0 24681012141618202224 noonmidnight time on day 1 (a) The World Health Organisation(WHO) has set guideline limits for nitrogen dioxide concentrations. These are 200 µg / m 3 for a one-hour average exposure and 40 µg / m 3 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[1] C123 June 2012

5. 5 (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 Number of vehicles 12341234 23592359 56785678 3154242461 9101112 noon 584472287277 Hour of the day 1314151617181920212223 24 midnight Number of vehicles 27528536345856644937216364362212 Use information from the tables to suggest an explanation for the shape of the graph............................................................................................................................................... [3] Turn over C123 June 2012

6. 6 (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 number1234 Nitrogen dioxide concentration286284285281 in µg / m 3 (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. best estimate = µg / m 3 [2] (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....................................................................................................................................... [2] [Total: 9] C123 June 2012

7. 4 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............................................................................................................................................... [6] C123 Jan 2013

8. 5 (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 number123456mean Nitrogen dioxide concentration123122120121124122 in µg/m 3 (i) Why is it an advantage to take six samples rather than one?...................................................................................................................................... [2] (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 = fromto µg/m 3 [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............................................................................................................................................... [3] [Total: 12] Turn over C123 Jan 2013

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