The aluminium in a used can is used up in the same way as coal burned for fuel.

Which resource comes from a deposit that is not replenished fast enough to keep up with human use?

• Coal deposits
• Wind energy
• Sunlight energy

Rain carries pollutants from mine waste into a nearby river. Which conclusion is supported?

• The flowing river makes those pollutants harmless
• The mine waste can reduce the river's water quality
• The river must have been polluted before mining began

In this model, producing equal masses of aluminium uses 120 energy units from ore and 12 by recycling. How many energy units are saved by recycling?

Why does recycling aluminium need less energy than extracting it from ore?

• Recycling changes aluminium into a metal that needs no heating
• Recycling makes aluminium ores release metal without electricity
• Recycling remelts metal instead of extracting it by electrolysis

A power plant burns more coal and oil. Which effect follows directly from burning these fossil fuels?

• More carbon dioxide enters the atmosphere
• More carbon is permanently stored underground as coal
• The remaining fuel deposits are replenished more rapidly

Priya says wood and coal are both non-renewable because today's supplies are limited. Which correction fits?

• Coal deposits can be replanted and grown again whenever a forest is planted
• Wood supplies are unlimited, even when trees are cut faster than they regrow
• Trees can regrow, but coal is not replenished on human timescales

A town finds that recycling its aluminium uses less energy and less new ore than replacing it with metal from ore. However, recycling costs the town more than landfill disposal. Which conclusion weighs both findings?

• Choose recycling because using less energy proves that the town will spend less money overall
• Recycling saves resources, but the town must weigh those benefits against its extra cost
• Choose landfill because lower disposal fees prove that it conserves more natural resources