AQA GCSE Chemistry Chemistry Paper 2 (Foundation), November 2021: Question 8

12 marks · Standard Demand difficulty · Extended Answer

Describe trends in electricity generation from oil and solar energy from a bar chart, explain the environmental impacts of burning oil, and evaluate solar energy as an alternative.

Practise this question

Question

Question text

08 This question is about fuels and energy.

Figure 6 shows the percentage of electricity generated in the UK between

2007 and 2017 using:

• oil

• solar energy.

Figure 6

08.1 Describe the changes in the percentage of electricity generated in the UK between

2007 and 2017 using:

• oil

• solar energy.

Use data from Figure 6 in your answer.

[3 marks]

08.2 Oil contains carbon and some sulfur.

*27* When oil is burned, the products of combustion may be released into the atmosphere.

Explain the environmental effects of releasing these products of combustion into

the atmosphere.

[6 marks]

08.3 Suggest one reason why using solar energy is a more sustainable way of generating

electricity than burning oil.

[1 mark]

08.4 Solar energy may not be able to replace the generation of electricity from

fossil fuels completely.

Suggest two reasons why.

*28* [2 marks]

Mark scheme

Show the mark scheme

Question 8

AO /

Question Answers Extra information Mark

Spec. Ref.

08.1 use of oil has decreased by 1 AO2

0.8% 4.10.1.1

use of oil has decreased from

1.3% to 0.5%

use of solar energy has 1

increased by 3.4%

use of solar energy has allow any value below 0.05% for

increased from 0% to 3.4% 2007

any one from:

• use of oil increased from 2007 allow use of oil was highest in 1

to 2009 2009

• no change in oil use between

2013 and 2015

• no change in solar energy use

between 2007 and 2009

• use of solar energy increased

most between 2013 and 2015

• between 2007 and 2011 more

oil was used and between

2013 and 2017 more solar

energy was used

if no other mark is awarded,

allow 1 mark for oil decreased

and solar energy increased

Question 8 continued

AO/

Question Answers Mark

Spec. Ref

Level 3: Relevant points (reasons/causes) are identified, given in 5‒6 AO2

08.2

detail and logically linked to form a clear account.

Level 2: Relevant points (reasons/causes) are identified, and there 3‒4 AO1

are attempts at logical linking. The resulting account is not fully

clear.

Level 1: Points are identified and stated simply, but their relevance 1‒2 AO1

is not clear and there is no attempt at logical linking.

20 No relevant content 0

Indicative content 4.9.2.2

4.9.2.3

• carbon dioxide produced 4.9.3.1

• (which is) a greenhouse gas 4.9.3.2

• (therefore) surface temperature increases

• (therefore) global warming

• (so) climate change

• (so) polar ice caps melt

• (so) increasing sea levels

• (so) flooding

• (so) extreme weather events

• (so) reduction in biodiversity

• (so) famine / drought

• sulfur dioxide produced

• (which causes) acid rain

• (so) damage to buildings / statues

• (so) damage to trees

• (so) damage to aquatic animals

• (so) respiratory problems in humans

• carbon / soot produced

• (which are) particulates

• (which cause) global dimming

• (so) respiratory problems in humans

• carbon monoxide produced

• (which is) toxic

Question 8 continued

AO /

Spec. Ref.

08.3 solar is (a) renewable (source of allow oil is (a) finite (source of 1 AO3

energy) energy) 4.10.1.1

AO /

Spec. Ref.

ignore references to cost AO3

08.4 any two from: 2 4.9.2.4

• sunshine is unreliable 4.10.1.1

• increased demand for energy

• lack of space

Total 12

How to answer it

Fuels, Combustion Products, and Alternative Energy Sources

What this question tests

This question assesses key ideas from AQA GCSE Chemistry: Chemical and Energy Changes in the Earth's Atmosphere & Using Resources:

Data analysis: Reading bar graphs precisely and describing comparative trends over time using quantitative figures.
Combustion pollutants (6-mark extended writing): Linking the combustion of elements in fuels (carbon and sulfur) to specific atmospheric pollutants and their resulting environmental effects.
Sustainability & Resources: Defining sustainable energy (renewables vs finite fossil fuels) and critically evaluating the real-world limitations of solar power.

Question 08.1

Trends in Electricity Generation (2007–2017)

Data Analysis & Bar Chart Interpretation • 3 Marks

✅ Model Answer (Any 3 marking points)

Oil overall decrease: The percentage generated from oil decreased from 1.3% in 2007 to 0.5% in 2017 (a decrease of 0.8%). [1 mark]
Solar overall increase: The percentage generated from solar energy increased from 0% in 2007 to 3.4% in 2017 (an increase of 3.4%). [1 mark]
Comparative detail or specific trend (any 1 from):
- Oil use peaked / was highest in 2009 (at 1.6%).
- Solar energy increased the fastest between 2013 and 2015 (by ~1.85%).
- Oil use did not change between 2013 and 2015 (remained at 0.6%).
- More electricity was generated from oil than solar between 2007 and 2011, but more from solar than oil from 2013 to 2017.
[1 mark]

🧠 Exam Technique: "Describe the changes..."

When an exam question instructs you to "Use data from Figure...":

You must quote numbers with units (%) from the chart to achieve full marks. Simply saying "oil went down and solar went up" is worth only 1 compensation mark.
Break your answer into two distinct parts: one for oil, one for solar energy, and finish with a comparison or peak turning point.

❌ Common Errors to Avoid

Reading the scale wrong: Each small grid square vertically represents 0.1%. Take time to count precisely (e.g., 2017 solar is exactly 3.4%, not 3.5%).
Forgetting the units: Stating "oil decreased by 0.8" without stating "%" can lose marks.

Question 08.2

Environmental Effects of Burning Oil

6-Mark Extended Response • Cause & Effect of Atmospheric Pollutants

🧠 How Level-Marked Questions Work

To reach Level 3 (5–6 marks), you must produce a detailed, logical account linking pollutant formed → mechanism → environmental effect for multiple products of combustion. Writing isolated bullet points without causes or effects limits you to Level 1 or 2.

✅ Model 6-Mark Structure

Pollutant Formed	How It Is Formed	Environmental & Atmospheric Effects
Carbon Dioxide (CO₂)	Complete combustion of carbon in oil: C + O₂ → CO₂	• It is a greenhouse gas. • Absorbs thermal radiation, leading to an increase in global temperatures (global warming). • Causes climate change, which results in melting polar ice caps, sea level rise, increased flooding, extreme weather, and loss of biodiversity/habitats.
Sulfur Dioxide (SO₂)	Combustion of sulfur impurities in oil: S + O₂ → SO₂	• Reacts with water vapor and oxygen in clouds to form acid rain. • Acid rain damages limestone buildings and statues, kills trees/damages forests, acidifies lakes killing fish and aquatic organisms, and causes respiratory issues in humans.
Carbon Particulates (Soot / C)	Incomplete combustion (limited oxygen supply)	• Cause global dimming by reflecting sunlight back into space before it reaches Earth. • Cause respiratory problems and lung damage in humans.
Carbon Monoxide (CO)	Incomplete combustion of carbon	• A colourless, odourless, toxic gas. • Binds irreversibly to haemoglobin in red blood cells, reducing their oxygen-carrying capacity.

💡 Key Knowledge: The Chain of Logic

Always state the entire chain:

CO₂ produced → Greenhouse gas → Global warming → Climate change → Melting ice caps / Flooding

Examiners deduct marks if students jump straight from "carbon dioxide causes polar bears to die" without explaining the greenhouse effect and climate change.

❌ Common Errors

Mixing up pollutants: Confusing the greenhouse effect with the ozone layer (carbon dioxide does not create holes in the ozone layer).
Saying CO₂ causes acid rain: While CO₂ is weakly acidic, GCSE chemistry strictly expects sulfur dioxide (and nitrogen oxides) as the cause of harmful acid rain.
Omitting sulfur: The question explicitly mentions oil contains "some sulfur". If you do not discuss sulfur dioxide, you miss a core requirement of the question.

Question 08.3

Sustainability of Solar Energy vs Burning Oil

Definitions & Resource Sustainability • 1 Mark

✅ Correct Answer

Solar energy is a renewable resource (it will not run out).
OR
Oil is a finite / non-renewable resource (it is being depleted faster than it is formed).

🧠 Exam Tip

Questions comparing sustainability usually hinge on the fundamental difference between renewable (replenished naturally at a faster rate than consumed) and finite resources.

Question 08.4

Why Solar Cannot Completely Replace Fossil Fuels

Limitations of Solar Power • 2 Marks

✅ Any TWO of the following reasons [1 mark each]:

Unreliable / Intermittent: Solar energy depends on weather/sunshine (no power generated at night; reduced output when cloudy or in winter).
Space requirements: Large areas of land/space are needed for solar panels to generate high amounts of electricity.
High / Increasing demand: The total national demand for electricity is too high to be met exclusively by current solar capacity.

❌ Major Mark Trap: Cost

The official mark scheme explicitly states:

"ignore references to cost"

Never write "solar panels are expensive to install" or "maintenance is too costly" when asked why an energy source cannot physically meet base demand.

Topics

Chemistry · C9: Chemistry of the Atmosphere · C10: Using Resources

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 2 (Foundation), November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.