Finite Resources & Recycling

Question 1

Which statement best explains why recycling aluminum cans saves energy compared with extracting aluminum from its ore?

Accepted Answer

Recycling aluminum uses only about 5 % of the energy needed to produce aluminum from bauxite ore.

Answer

Extracting aluminum from ore releases no greenhouse gases, while recycling aluminum does release large amounts of carbon dioxide.

Answer

Recycling aluminum requires the same amount of energy as extraction because the metal must be melted in both processes.

Answer

The amount of energy saved by recycling aluminum is negligible because most aluminum products are already made from recycled material.

Question 2

A town needs 1,000 kg of copper for new wiring. It has two options: 1. Mine copper from ore. Cost = 6 per kg (total 6,000) and uses 25,000 MJ of energy. 2. Recycle copper wire. Cost = 8 per kg (total 8,000) and uses 5,000 MJ of energy, saving 800 kg of copper ore from being mined. Which statement best describes the trade‑off between the higher monetary cost of recycling and the benefit of conserving resources and energy?

Accepted Answer

Recycling costs 2,000 more but saves 20,000 MJ of energy and conserves 800 kg of ore, so the environmental benefit outweighs the extra cost.

Answer

Recycling costs 2,000 more and saves only 800 kg of ore, which is negligible, so it is not worth recycling.

Answer

Recycling costs 2,000 less and saves energy, making it clearly the better choice.

Answer

Recycling costs 2,000 more but saves energy and ore; however, because it is more expensive, the town should only recycle if it receives a special grant.

Question 3

Which of the following statements correctly identifies a natural resource that is finite and gives a valid reason for why it is finite?

Accepted Answer

Coal is a finite resource because it forms from ancient plant matter over millions of years, so the amount we mine each year cannot be replaced within human time scales.

Answer

Freshwater is a finite resource because the oceans continually lose water to outer space, so the total supply will eventually run out.

Answer

Wind is a finite resource because the atmosphere’s moving air will be used up after a few decades of generating electricity.

Answer

Solar energy is a finite resource because the Sun will exhaust its fuel and cease shining within the next hundred years.

Try three questions

Which statement best explains why recycling aluminum cans saves energy compared with extracting aluminum from its ore?

Which of the following statements correctly identifies a natural resource that is finite and gives a valid reason for why it is finite?

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