These eight questions move from classifying to calculating to judging. Try each on paper before opening the answer.
They cover the cluster on green technology. The timed practice session builder can turn the set into a timed run.
Questions
Question 1 (2 marks). Classify a wind turbine and a food waste composter by purpose.
Answer
Wind turbine: energy supply. Composter: waste handling.
Reason: the turbine produces electricity from moving air, while the composter turns food scraps into soil improver.
Question 2 (2 marks). An LED lamp gives the same light as an old lamp but uses less electricity. State its purpose group and give a reason.
Answer
Energy saving. It does the same job using less electrical energy, so less fuel or other energy source is needed to supply it.
Question 3 (3 marks). A fictional generator uses 0.70 kg of CO₂ per kWh. A school uses 120 kWh in one day. Calculate the emissions.
Answer
Emissions = 120 × 0.70 = 84 kg of CO₂. This assumes the school uses 120 kWh and only running emissions are counted.
Question 4 (3 marks). Option P emits 0.20 kg per kWh and option Q emits 0.50 kg per kWh. For 100 kWh, find how much less P emits.
Answer
P: 100 × 0.20 = 20 kg. Q: 100 × 0.50 = 50 kg.
P emits 30 kg less than Q for the same energy.
Question 5 (4 marks). A solar system costs RM30 000 to install and saves RM25 a day compared with the grid. Calculate the payback time in days, and state one assumption.
Answer
Payback = 30 000 ÷ 25 = 1 200 days, which is about 3.3 years.
Assumption: the saving stays RM25 every day, so the system supplies the same amount each day.
Question 6 (3 marks). A class recycles 75 of its 100 drink cans each week. Explain how this conserves a resource.
Answer
Recycling means the metal is reprocessed into new items, so less new raw material needs to be mined. It also reduces the waste sent to landfill.
Supporting number: 75 of 100 cans, or 75%, are kept out of the landfill each week.
Question 7 (3 marks). State the difference between reuse and recycle, using a bottle as the example.
Answer
Reuse: fill the same bottle again with another drink. The bottle is used as it is.
Recycle: break the bottle down and process the material into new items. The material is reprocessed.
Question 8 (5 marks). A showerhead claims: “Uses at least 40% less water.” Before fitting it, a shower used 15 litres a minute. After fitting, it uses 10 litres a minute. Evaluate the claim.
Answer
Saving = 15 − 10 = 5 litres a minute. As a percentage, 5 ÷ 15 × 100 = about 33%.
The criterion is 40%, so the claim is not supported: the saving is about 33%, below 40%. A limit is that the flow may depend on the water pressure at different homes.
If you got these wrong
- Questions 1 and 2: revisit classifying green-technology applications.
- Questions 3 to 5: work through comparing energy choices using supplied data.
- Questions 6 and 7: read explaining resource conservation.
- Question 8: see evaluating claims using a stated criterion.
A mistake log shows which step repeats. If you want a teacher to read your verdicts and conclusions, see online one-to-one Science tuition.