Common atmospheric pollutants (AQA GCSE Chemistry)

Exam Questions

2 hours24 questions
1a2 marks

This question is about the combustion of fossil fuels.

Methane, CH4, can undergo complete combustion to produce carbon dioxide and water.

Why is methane a hydrocarbon?

1b2 marks

Balance the symbol equation for the complete combustion of methane.

___ CH4   +   ___ O2    →   ____ CO2   +   ___H2O  

1c1 mark

Methane can also undergo incomplete combustion to produce carbon monoxide and water.

Complete the sentence to explain why this happens.

Incomplete combustion happens because there is not enough ________________________ for the fuel to burn in. 

1d3 marks

People often have carbon monoxide detectors in their homes to detect the presence of this gas.

Which properties of carbon monoxide make this necessary? 

Tick (✓) three boxes.

 It is toxic  
 It is acidic   
 It is colourless   
 It is odourless   
 It is a particulate   
 It is alkaline  

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2a3 marks

This question is about atmospheric pollution.

A fuel is burnt and releases carbon dioxide, nitrogen dioxide and water vapour.

Which elements are present in the fuel?

Tick (✓) three boxes.

 oxygen  
 carbon  
 nitrogen  
 sulfur  
 hydrogen  
2b2 marks

Nitrogen dioxide and carbon dioxide are both pollutants.

Draw one line from each pollutant to the polluting effect. 

pollutants-and-their-effects-match-up
2c1 mark

Carbon dioxide and nitrogen dioxide are both produced when a fuel burns in a car.

Which other gas is also produced? 

Circle one answer.

ammonia sulfur carbon monoxide

2d2 marks

Complete the sentences to describe how we can test for the presence of carbon dioxide gas. 

cloudy orange limewater
litmus paper colourless bromine water



To test for carbon dioxide gas _________________ is added.

If carbon dioxide is present the solution will turn ____________________. 

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3a1 mark

This question is about sulfur dioxide.

Sulfur dioxide is a pollutant produced when sulfur and oxygen react during combustion.

Complete the word equation to show the formation of sulfur dioxide.

sulfur   +   __________________________________________

3b3 marks

Complete the sentences about the formation of sulfur dioxide.

The formula of sulfur dioxide is   

SO2.

S2O.

SO.

When sulfur reacts with oxygen, the sulfur is   

reduced.

neutralised.

oxidised.

Sulfur dioxide reacts with rainwater to form    

sulfur trioxide.

sulfuric acid.

sulfur.

3c2 marks

Give two problems sulfur dioxide causes.

3d1 mark

Sulfur dioxide dissolves in water to produce an acidic solution.  

What colour would the solution turn if sulfur dioxide was bubbled through a solution containing universal indicator?

Tick (✓) one box. 

 Red  
 Green  
 Purple  
3e
Sme Calculator
2 marks

Figure 1 shows the percentage of sulfur dioxide released by human activities.

Calculate the percentage of sulfur dioxide released by transport. 

Figure 1

sulfur-dioxide-production-pie-chart 

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4a2 marks

In the UK, fossil fuels are burnt to release energy. This is how most electricity is generated in the UK.

Figure 1 shows some of the substances released when fossil fuels are burned. 
 

 Figure 1

aqa-gcse-9-3e--tq4a-power-station


Name two substances released that are greenhouse gases.

4b1 mark

Give the environmental effect of smoke particles.

Circle one answer. 

Global warming Global dimming Acid rain

4c1 mark

What type of combustion produces smoke particles?

4d1 mark

Which substance released from the power station in Figure 1 will result in the erosion of limestone?

4e1 mark

Why will fewer power stations be burning fossil fuels in the future? 

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5a1 mark

This question is about oxides of nitrogen.

Nitrogen has an atomic number of 7.

Complete the electronic structure of nitrogen.

 _ECPO~F8_shells-

5b4 marks

When petrol is burnt, oxides of nitrogen are released into the atmosphere.

Complete the sentences using the words in the box to help you. 

high poisoning nitrogen respiratory problems
nitric acid low carbon dioxide oxygen global dimming

Oxides of nitrogen are produced when nitrogen reacts with ________________ in the air.

This reaction occurs at __________________ temperatures.

Oxides of nitrogen react with clouds to form  ______________________.

Oxides of nitrogen cause acid rain and ____________________.

5c1 mark

Which reaction releases energy from petrol? 

Tick (✓) one box. 

 Respiration  
 Combustion  
 Neutralisation  
 Decomposition  

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61 mark

Pollutants released from burning fuels can negatively affect health and the environment.

Which of the following is not the correct effect for the given pollutant?

  Pollutant  Effect
A carbon dioxide global warming
B sulfur dioxide acid rain
C oxides of nitrogen respiratory problems
D particulates poisonous

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    1a2 marks

    Older automobiles that are still in use are tested every year to monitor the levels of pollution in their exhaust fumes.

    The maximum allowed percentages of exhaust pollutants for petrol cars are shown in the table.

      Percentage cap of exhaust pollutant

    Car age (years)

    Carbon monoxide

    Unburned hydrocarbons

    16−24

    0.30

    0.02

    3−16

    0.20

    0.02


    Explain how burning petrol in a car produces carbon monoxide.

    1b3 marks

    Suggest three reasons why the maximum allowed percentage of carbon monoxide for newer cars is much less than for older cars.

    1c2 marks

    Give two reasons for there being a maximum allowed percentage of unburned hydrocarbons present in exhaust fumes.

    1d2 marks

    Exhaust fumes contain oxides of nitrogen which are also pollutants.

    Describe how oxides of nitrogen are produced in car engines.

    1e2 marks

    Advances in technology led to the production of catalytic converters. 

    These are fitted to car exhausts to reduce the amount of pollutants they release.

    Nitrogen dioxide is a pollutant that reacts to produce nitrogen and oxygen in catalytic converters.

    Complete and balance the equation for the reaction.

    ____ NO2 ⟶ ________ + ____ O2 

    1f2 marks

    Give two effects of atmospheric pollution which are reduced by using catalytic converters.

    1g1 mark

    The catalyst in catalytic converters is a mixture of three elements.

    Where in the periodic table are these elements most likely to be found?

    Tick one box. 

    Halogens  
    Group 2  
    Transition metals  
    Group 6  

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    21 mark

    Catalytic converters are usually made up of three elements and are fitted into car exhausts to reduce the effect of pollutants.

    Which group of elements would most likely be used?

    • Alkali Metals 

    • Halogens

    • Transition metals

    • Noble gases 

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    31 mark

    Limestone is eroded by acid rain.

    Which substance falls as acid rain?

    • SO2

    • HCl

    • H2SO4

    • NO2

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    4a4 marks

    County planners are attempting to protect the environment around a reservoir that is surrounded by trees.

    It is a large reservoir with only one access road and a car park that is positioned a few kilometres from the reservoir. 

    A steam train has been installed to ferry visitors from the car park to the reservoir, accomodation or activities.

    A map of the area is shown in Figure 1.

    Figure 1

    aqa-gcse-9-3m-q2a-county-plan-map

    The steam train uses coal for the furnace which causes environmental problems.

    Explain why.

    4b3 marks

    The planners have stated that the overall amount of carbon dioxide added to the atmosphere must be kept the same to account for the train. 

    The steam train would be considered as ‘carbon neutral’ if wood were used instead of coal.

    Suggest why.

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    5a6 marks

    This question is about biodiesel.

    Biodiesel can be made from many types of vegetable oils. 

    A group of scientists compared the exhaust emissions when fossil diesel (diesel produced from crude oil) or biodiesel were used as fuels.

    Some of the relative amounts of these exhaust emissions are shown in the bar chart in Figure 1.

    Figure 1

    aqa-gcse-9-3m-q3a-exhaust-emissions

    Explain the environmental benefits of using biodiesel over diesel, using the information in Figure 1.

    5b6 marks

    Biodiesel is also known as a green fuel because the life-cycle emission of carbon dioxide from biodiesel is less than that from fossil diesel. 

    Use the information above to explain why the contribution of biodiesel to global warming is considered to be much less than that of fossil diesel.

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    6a4 marks

    This question is about the effects of sulfur dioxide in the atmosphere.

    Fossil fuels contain impurities of sulfur. 

    When combustion occurs, sulfur dioxide is produced. 

    Measures are taken to prevent sulfur dioxide from being released into the atmosphere.

    Explain why it is important that sulfur dioxide is not released into the atmosphere.

    6b6 marks

    Three of the methods used to remove sulfur dioxide from gases produced when fossil fuels are burned are, dry gas desulfurisation (D), wet gas desulfurisation (W) and seawater gas desulfurisation (S)

    Information about the three methods is given in Figure 1 and Table 1 below.

    Figure 1

    aqa-gcse-9-3m-q4b-sulfur-removal-graph

    Table 1

    Method Material used How it is obtained Management of waste material
    D Calcium oxide, CaO Thermal decomposition of CaCO3
    CaCO3  →  CaO  +  CO2
    Solid waste is sent to landfill.
    W Calcium carbonate, CaCO3 Quarrying Solid waste is sold for use in buildings.
    Carbon dioxide is released into the atmosphere.
    S Seawater From the sea Liquid waste is returned to the sea.


    Evaluate the three methods of removing sulfur dioxide from the waste gases during the combustion of fossil fuels.

    Compare the three methods, using the data provided to justify your conclusion.

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    71 mark

    Incomplete combustion occurs when there is insufficient oxygen for a reaction.

    Which are the two main substances formed during incomplete combustion, aside from water?

    • Particulates and carbon monoxide 

    • Soot and sulfur dioxide 

    • Carbon dioxide and carbon monoxide 

    • Oxides of nitrogen and sulfur dioxide 

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    81 mark

    Cars running on fossil fuels contribute a high amount of pollutants into the atmosphere, one of which is carbon dioxide. 

    Which other gas is produced by the internal combustion engine in a car?

    • Ammonia

    • Argon

    • Oxides of nitrogen

    • Nitrogen

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    1a3 marks

    This question is about sulfur.

    Describe the structure of an atom of sulfur.

    Use your periodic table to help you.

    1b3 marks

    Limestone is eroded as a result of burning fossil fuels containing sulfur.

    Explain how this happens.

    1c3 marks

    Explain why sulfur dioxide has a low melting point.

    You should refer to its structure and bonding in your answer.

    1d1 mark

    Name one other pollutant gas that results in the erosion of limestone. 

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    2a2 marks

    Natural gas is a fossil fuel consisting mainly of methane.

    When methane burns it can produce carbon monoxide as well as carbon dioxide.

    Explain why carbon monoxide is produced when methane is burned. 

    2b3 marks

    Write a balanced symbol equation for the combustion of methane, CH4, to produce carbon monoxide, CO and one other product.

    2c1 mark

    Give one hazard associated with carbon monoxide. 

    2d2 marks

    Wood is more sustainable than natural gas and other fossil fuels.

    Suggest two reasons why. 

    2e3 marks

    Complete the energy level diagram for the combustion of methane.

    On the completed diagram, label: 

    • activation energy 
    • overall energy change

    comvustion-of-methane-reaction-profile

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    3a4 marks

    This question is about pollutants.

    Fossil fuels, such as coal, are burned to release energy.

    Hydrogen, sulfur, and carbon are all elements found in coal.

    Name two products released when coal burns that have a negative effect on the environment.

    State the impact each of the products you have named have.

    3b2 marks

    Oxides of nitrogen also impact the environment.

    Explain how oxides of nitrogen are formed in car exhausts. 

    3c2 marks

    Describe two effects of oxides of nitrogen being released into the atmosphere.

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    4a6 marks

    Fossil fuels produce sulfur dioxide when they burn due to containing sulfur impurities.

    Sulfur dioxide has many environmental effects such as acid rain so its release should be avoided.

    To overcome this issue, three methods are used to ensure it is removed from the other gases formed during combustion: 

    • Dry gas desulfurisation (DG)
    • Wet gas desulfurisation (WG) 
    • Seawater gas desulfurisation (SG) 

    Information about the three methods is given in the bar chart in Figure 1 and Table 1.

    Figure 1

    aqa-gcse-9-3h-tq4a-desulfurisation-table

    Table 1 

    Method  Substances used  Method of obtaining substance Disposal of waste material
    DG Calcium oxide

    Thermal decomposition of calcium carbonate 

     

     Landfill receives solid waste
    WG Calcium carbonate Quarrying

     CO2 released into atmosphere 

     Solid waste is sold to use in buildings 

    SG Seawater The sea

    Liquid waste goes into the sea 

    Evaluate the three methods of removing sulfur from waste gases. 

    4b2 marks

    Sulfur dioxide will dissolve in water.

    Explain what colour universal indicator will turn when it is added to the solution.

    4c1 mark

    All acids contain the same ion.

    What is the formula of this ion? 

    4d2 marks

    Hydrochloric acid is a strong acid.

    Explain why a strong acid has a low pH.

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    5a1 mark

    This question is about pollution.

    Electricity can be generated through burning fossil fuels, such as coal, in power stations.

    Doing this releases harmful pollutant gases such as sulfur dioxide (which causes acid rain) and carbon dioxide.

    Limestone can be used to prevent sulfur dioxide entering the atmosphere, however it also releases 'locked up' carbon dioxide. 

    Figure 1 

    aqa-gcse-9-3h-tq5a-power-station-emissions


    How does limestone remove sulfur dioxide?

    5b1 mark

    How is carbon dioxide released from the limestone in Figure 1?

    5c4 marks

    Two products are produced as a result of incomplete combustion of the fuel.

    Name these two products and give a reason for each one why it should not be released into the environment.

    5d1 mark

    Why does the release of carbon dioxide cause an environmental problem?

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