Question 1
A plastic beaker used to hold liquids in a laboratory is commonly manufactured using
Not quite. Polyethylene is a close second, and it makes lab wash bottles. QCAA’s 2025 table gives polypropylene the edge on both demands that matter: excellent rather than good chemical resistance, and heat resistance up to 135 °C rather than 120 °C. In 2023, 24.5% of Queensland students chose (A).
That is it. Step through the hints below to see why. In 2023, 57.6% of Queensland students chose (B).
Not quite. Polylactic acid softens at about 60 °C and is designed to break down. A beaker that holds hot liquids and chemicals needs a plastic that does neither. In 2023, 10.0% of Queensland students chose (C).
Not quite. PVC resists chemicals, but it softens at about 80 °C, so it cannot take hot liquids or a steam steriliser. In 2023, 7.6% of Queensland students chose (D).
A laboratory beaker holds acids, alkalis and solvents. It is washed, heated and often sterilised with steam at about 121 °C.
So it needs chemical resistance and heat resistance. Every option can be made clear or translucent, so seeing the level does not separate them.
Polylactic acid softens at about 60 °C and PVC at about 80 °C, so both fail the heat demand. That rules out (C) and (D).
QCAA’s own 2025 table settles it. Polypropylene has excellent chemical resistance against polyethylene’s good, and heat resistance up to 135 °C against 120 °C.
QCAA’s 2025 marking guide lists plastic beakers among the uses of polypropylene. That is (B).
A laboratory beaker needs chemical resistance and heat resistance. Polypropylene is the best of the four on both, and QCAA’s 2025 marking guide names “plastic beakers” among its suitable applications. The 2019 syllabus that 2023 students sat listed polypropylene for “laboratory equipment, electronics and automobile products”.
The most common wrong answer was (A), chosen by 24.5%. Polyethylene and polypropylene look alike and both resist chemicals. The heat a lab puts a beaker through is what separates them.
QCAA did not publish a band for this question. It reads as simple familiar because one recall step takes you from a common lab item to its plastic. For 2026, all four options are gone from Unit 4. Polyethylene, polypropylene and PVC are in Unit 2, which the external exam does not assess, and polylactic acid is not in the syllabus at all. What transfers is the comparison. 2025 Question 16 gave a property table for polypropylene and polyethylene, and finding the property that decides the job is still the skill.
If I had to guess where you might lose marks, it would be picking polyethylene because it is the plastic you know from bottles and bags. The two are close, so the deciding property, heat resistance, has to come from what the job puts the beaker through.
Only mark this done when you could do it without help. Reading the solution does not count.
Question wording and any figures are from the 2023 QCAA Engineering external assessment, © State of Queensland (QCAA) 2023, licensed under CC BY 4.0, and have been adapted, except where a third-party source is named. Tangent Tuition is not affiliated with the QCAA.
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