Students were concerned about how human activities may threaten the environment by causing air pollution. The students decided to focus on one problem caused by air pollution – the impact of acid rain in their region. First they researched acid rain and made a fact file. This is shown on Fig. 12 (Insert 2). The students decided to test the following hypotheses: Hypothesis 1 The acidity of rainfall is affected by the direction of the wind Hypothesis 2 Rainfall is more acidic after a period of dry weather

1. (a)(i)State two human activities which could cause air pollution. 1 .......................................................................................................................................................... 2 ..........................................................................................................................................................[2]
2. (a)(ii)Describe three effects of air pollution on the natural environment. 1 .......................................................................................................................................................... 2 .......................................................................................................................................................... 3 ..........................................................................................................................................................[3]
3. (b)Look at Fig. 13 (Insert 2) which is a sketch map of the area where the students live. What is meant by the term prevailing wind?[1]
4. (c)(i)The students realised that this investigation would be long-term, so they agreed to do their investigation every day for four months. They set up a recording station in the grounds of their school. Each day they recorded the following: • wind direction; • amount of rain that had fallen in the previous 24 hours; • pH value of any rainwater collected. They recorded their results as a data log. Part of this log is shown on Table 6 (Insert 2). Describe how they collected their data. Refer to equipment used in your answer. The answer for pH has been done for you. Wind direction ........................................................................................................................................ Amount of rain that had fallen ................................................................................................................ pH They used a pH meter or pH strips to measure the pH value of rainwater.[2]
5. (c)(ii)Why did the students decide to do their investigation over four months?[2]
6. (c)(iii)What difficulties might the students have had in collecting their data, which may have affected their results?[3]
7. (c)(iv)Using their data log, they produced the summary in Table 7 (Insert 2). By studying this summary, what conclusion could the students make about Hypothesis 1 The acidity of rainfall is affected by the direction of the wind? What evidence from Table 7 supports their conclusion?[3]
8. (c)(v)Use information from Figs 12 and 13 (Insert 2) to explain why the level of acidity in rainfall varies with wind direction.[3]
9. (d)(i)Next, the students looked at Hypothesis 2 Rainfall is more acidic after a period of dry weather. Using their data log again, the students produced the summary in Table 8 (Insert 2). Use the results recorded in bold in Table 8 to complete the scatter graph, Fig. 14 (opposite) and draw in a best-fit line. [Figure 14][3]
10. (d)(ii)The students accepted Hypothesis 2 Rainfall is more acidic after a period of dry weather. Do you agree with them? Support your answer with evidence from Fig. 14.[2]
11. (e)(i)The students wanted to investigate the impact of another kind of pollution. Suggest a possible hypothesis about water pollution and describe appropriate data collection methods.[4]
12. (e)(ii)Having completed their investigation of water pollution, what recommendations might the students have made to a water authority about how to reduce the level of pollution?[2]

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