Chemistry of the EnvironmentCambridge IGCSE Chemistry: Topic test

20 questions, 54 marks

Cambridge IGCSE Chemistry

Chemistry of the Environment topic test

Total 54 marks

Name

Class

Date

1
A laboratory assistant is given two unlabelled colourless liquids, X and Y, and must find out whether each is pure water. She adds a few drops of each liquid to separate samples of white anhydrous copper(II) sulfate powder and separately to samples of blue anhydrous cobalt(II) chloride paper.
(a)
Liquid X turns white anhydrous copper(II) sulfate blue and turns blue anhydrous cobalt(II) chloride paper pink. What does this show about liquid X?
[1 mark]
ALiquid X definitely contains water, but may not be pure
BLiquid X contains no water at all
CLiquid X is definitely pure water
DLiquid X is an acid, not water
(b)
To check whether liquid X is pure water rather than water containing dissolved impurities, which further test should the assistant carry out?
[1 mark]
AAdd more anhydrous copper(II) sulfate and see if it turns blue a second time
BMeasure its density only, since pure water always has a unique colour
CAdd universal indicator and check that it turns green
DMeasure its melting point and boiling point and compare them with 0°C and 100°C
(c)
The assistant needs distilled water rather than tap water to prepare a standard solution for the laboratory's next experiment. Explain why distilled water is used instead of tap water for this purpose.
[2 marks]
Total for question 1: 4 marks
2
An environmental monitoring station beside a busy motorway records the gases in the air over one day. Compared with a rural site 20 km away, the motorway site shows much higher levels of carbon monoxide, oxides of nitrogen and small particulates, but a similar percentage of nitrogen and oxygen.
(a)
Which pollutant detected at the motorway site is mainly produced by the incomplete combustion of fuel in vehicle engines, and is dangerous because it is toxic even in small quantities?
[1 mark]
ACarbon dioxide
BNitrogen
CCarbon monoxide
DOxygen
(b)
The oxides of nitrogen detected at the motorway site form inside a car engine. Which statement correctly explains their source?
[1 mark]
AThey form when nitrogen and oxygen from the air react together at the high temperature inside the engine
BThey form when unburned petrol reacts directly with the metal engine casing
CThey are released unchanged from the fuel tank, since petrol already contains oxides of nitrogen
DThey form only when the engine is switched off and cooling down
(c)
State one adverse effect on human health of the particulates detected at the motorway site, and state one adverse environmental effect of the oxides of nitrogen detected there.
[2 marks]
Total for question 2: 4 marks
3
A commercial market garden has been growing tomatoes in the same soil for several seasons without adding any fertiliser, and yields have been falling. Soil tests show the crop has removed large amounts of nitrogen, phosphorus and potassium compounds from the soil.
(a)
Explain why adding an NPK fertiliser to the soil would be expected to improve the tomato yield, and name one compound that could supply the nitrogen content of such a fertiliser.
[3 marks]
(b)
Ammonium nitrate fertiliser is manufactured industrially by reacting ammonia gas with nitric acid. Describe the type of reaction taking place, and explain, using the idea of solubility, why ammonium nitrate is a particularly effective fertiliser for delivering nitrogen quickly to a plant's roots.
[4 marks]
Total for question 3: 7 marks
4
Heavy rain washes fertiliser that was recently applied to fields beside a river into the water. Downstream, a reservoir that supplies a town's drinking water shows a sudden increase in the growth of algae covering the surface, and later a large number of fish are found dead in the reservoir.
(a)
Explain, step by step, how the fertiliser runoff has led to the death of the fish in the reservoir.
[6 marks]
(b)
The water company that treats this reservoir water before supplying it to the town explains that its standard treatment process removes solids, unpleasant tastes and microbes, but is not designed to remove all the dissolved nitrate. Describe the stages of the standard domestic water treatment process, and suggest why dissolved nitrate ions are more difficult to remove than the substances the process is designed for.
[6 marks]
Total for question 4: 12 marks
5
A power company burns coal that contains sulfur compounds in an old power station to generate electricity. Downwind of the power station, a forest has shown declining tree health over several decades, and lakes in the area have become noticeably more acidic.
(a)
Which gas, produced when the coal is burned, is mainly responsible for the increasing acidity of the lakes downwind of the power station?
[1 mark]
ANitrogen
BSulfur dioxide
COxygen
DWater vapour
(b)
The power company is considering fitting flue gas desulfurisation, which passes the waste gases through a slurry of calcium oxide before they leave the chimney. Which statement best explains how this reduces the acid rain problem?
[1 mark]
ACalcium oxide cools the waste gases so that sulfur dioxide condenses into a harmless liquid
BCalcium oxide converts sulfur dioxide into oxygen gas, which is then released instead
CCalcium oxide filters out solid particulates only and has no effect on sulfur dioxide
DCalcium oxide reacts with sulfur dioxide, neutralising it before it is released into the atmosphere
(c)
Besides fitting flue gas desulfurisation, suggest two other strategies the power company or the government could use to reduce the amount of acid rain caused by this power station.
[2 marks]
Total for question 5: 4 marks
6
A community on a small island has no piped water supply and relies on seawater. Engineers are designing a desalination unit that heats seawater to produce steam, then cools the steam back into liquid water in a separate collecting vessel, leaving the dissolved salts behind in the original container.
(a)
What is the name of this separation process, in which a liquid is turned into a vapour and then condensed to collect it separately from dissolved solids?
[1 mark]
AFiltration
BCrystallisation
CSimple distillation
DChromatography
(b)
Once collected, which property could the engineers measure to confirm that the water produced is pure rather than still containing dissolved salt?
[1 mark]
AIts colour, since pure water and salt water look different
BIts boiling point, which should be exactly 100°C for pure water at standard pressure
CIts smell, since salty water always has a noticeable odour
DIts ability to conduct electricity, which should be very high for pure water
(c)
State two substances, other than dissolved salts, that water from a natural source such as the sea or a river may contain, and for one of them state whether its presence in drinking water is beneficial or harmful.
[2 marks]
Total for question 6: 4 marks
7
A greenhouse nursery grows seedlings in trays of soil with no natural rainfall reaching them, and relies entirely on the nutrients the nursery adds by hand. After several weeks without any added fertiliser, the seedlings show poor, stunted growth.
(a)
State the three main elements supplied by an NPK fertiliser, and explain why the seedlings have grown poorly without any added fertiliser.
[3 marks]
(b)
The nursery manager considers switching from a solid granular fertiliser, which must first dissolve in the watering water, to a fertiliser made from ammonium nitrate dissolved directly in the water used to irrigate the trays. Suggest, with a reason based on solubility, why the ammonium nitrate solution might improve the seedlings' growth more quickly than the granular fertiliser, and suggest one disadvantage of applying fertiliser in this dissolved form.
[4 marks]
Total for question 7: 7 marks
8
A government report investigates why a country's greenhouse gas emissions and its water pollution levels have both risen over the past twenty years. Much of the increase is linked to a large expansion in livestock farming, where increasing numbers of cattle are kept, and farmers have increased their use of nitrogen fertiliser to grow more animal feed on the same land.
(a)
Explain, with reference to the gases produced, how the expansion of livestock farming described in the report has contributed to increased global warming, and suggest one strategy that could reduce this contribution.
[6 marks]
(b)
Explain how the increased use of nitrogen fertiliser to grow animal feed, described in the report, could lead to increased water pollution in nearby rivers and lakes, and explain how this differs from the direct effect that increased cattle numbers have on greenhouse gas emissions in part (a).
[6 marks]
Total for question 8: 12 marks

End of questions