A refrigerated warehouse is changing its electricity supply. It will only accept a plan with mean carbon dioxide emissions below 100 g per kWh of electricity supplied.
The supplier gives the mean carbon dioxide emissions from four methods of generating electricity.
| Method of generating electricity | Mean carbon dioxide emissions (g per kWh) |
|---|---|
| Gas-fired power station | 460 |
| Gas-fired power station with carbon capture | 130 |
| Onshore wind turbines | 12 |
| Nuclear power station | 15 |
Four supply plans are available.
| Plan | Electricity supplied by each method |
|---|---|
| W | 75% onshore wind turbines and 25% gas-fired power station |
| X | 55% nuclear power station and 45% gas-fired power station with carbon capture |
| Y | 80% nuclear power station and 20% gas-fired power station |
| Z | 25% onshore wind turbines and 75% gas-fired power station with carbon capture |
Which plan meets the warehouse's limit?
Plan X
Plan Z
Plan Y
Plan W
109 exam-style questions on OCR GCSE Chemistry 6.3 Interpreting and interacting with earth systems, covering 6.3.1 Formation and evolution of the atmosphere, 6.3.2 The greenhouse effect and climate change, 6.3.3 Sources and problems of atmospheric pollutants, and 6.3.4 Producing potable water. Each one has a worked solution and a mark scheme showing where the marks go.