AQA GCSE Chemistry Chemistry Paper 2 (Higher), November 2021: Question 1

✅ Mark Scheme Model Answer

• Mark 1 (Oil): Oil use decreased from 1.3% to 0.5% (or decreased by 0.8%).
• Mark 2 (Solar): Solar energy increased from 0% to 3.4% (or increased by 3.4%; allow any 2007 value < 0.05%).
• Mark 3 (Key feature - any one):
  • Oil peaked / was highest in 2009 (at 1.6%).
  • Oil stayed constant between 2013 and 2015 (at 0.6%).
  • Solar stayed at ~0% between 2007 and 2009.
  • Solar had its biggest increase between 2013 and 2015.
  • More oil than solar was used from 2007 to 2011, but more solar than oil from 2013 to 2017.

🧠 Exam Technique: "Describe using data"

• Always quote start and end values: Don't just say "it went down". State clearly: "decreased from 1.3% in 2007 to 0.5% in 2017".
• Check graph scale increments: On the y-axis, 5 small squares = 0.5%, so 1 small square = 0.1%. Misreading the grid is the easiest way to drop marks.
• Look for turning points: A 3-mark trend question usually needs an extra detail such as a peak, a plateau, or a crossover point.

❌ Common Errors

• Writing qualitative statements only: "oil went down and solar went up" only scores 1 mark as a fallback if no data is given!
• Misreading 2007 oil: quoting 1.25% instead of counting the exact grid lines (1.3%).
• Forgetting units: leaving off the "%" symbol when quoting figures.

📐 Quick Data Check

Oil: 2007 = 1.3%, 2017 = 0.5% → Change = 1.3% − 0.5% = −0.8%

Solar: 2007 = 0.0%, 2017 = 3.4% → Change = 3.4% − 0.0% = +3.4%

✅ Model 6-Mark Answer Structure

To achieve Level 3 (5–6 marks), you must identify pollutants AND link them logically to their specific environmental consequences:

• Carbon dioxide (CO₂): Combustion of carbon forms carbon dioxide. CO₂ is a greenhouse gas that traps thermal radiation, causing global warming. This drives climate change, leading to melting polar ice caps, sea-level rise, increased coastal flooding, and severe weather.
• Sulfur dioxide (SO₂): Sulfur in the fuel reacts with oxygen to form sulfur dioxide gas. This dissolves in rain clouds to produce acid rain, which acidifies lakes (killing aquatic life), damages trees/forests, and corrodes limestone buildings and statues.
• Carbon particulates (soot): Incomplete combustion produces unburnt carbon particulates, which reflect sunlight back into space causing global dimming, and irritate human respiratory systems.
• Carbon monoxide (CO): Incomplete combustion also produces carbon monoxide, which is a colourless, odourless, toxic gas.

✅ Mark Scheme Answer

• Solar energy is a renewable source of energy (it will not run out).
• OR: Oil is a finite / non-renewable resource (it will run out).

💡 Definition: Sustainable & Renewable

Renewable resource: An energy resource that is replenished at a faster or equal rate to which it is consumed, meaning it will not run out (e.g. solar, wind, tidal).

Finite resource: Being used up faster than it naturally forms; once depleted, it cannot be replaced (e.g. crude oil, coal, natural gas).

✅ Mark Scheme Answers (Any TWO)

1. Sunshine is unreliable / intermittent: Solar panels cannot generate electricity at night and generate significantly less on cloudy/overcast days.
2. High / increasing energy demand: Current solar technology cannot match the continuous baseload demand required by the national grid.
3. Lack of space / land: Huge surface areas of land are required to install enough solar farms to produce large-scale power.

❌ Examiner Trap: "Ignore references to cost"

The mark scheme strictly states: ignore references to cost.

• Writing "solar panels are expensive to install" will score 0 marks.
• Focus purely on physical, geographic, and operational limitations: intermittency (weather/night) and land area required.