Work through these eight questions in order, and write your own answer before you open each one. They cover all four lessons in industrial chemistry.
The timed practice session builder can turn the set into a timed run.
Questions
Question 1 (2 marks). Explain why bronze, an alloy of copper and tin, is harder than pure copper.
Answer
Tin atoms are a different size from copper atoms, so they disturb the regular layers of copper atoms. The layers slide less easily, so bronze is harder than pure copper.
Question 2 (3 marks). Choose a material (polymer, glass or ceramic) for each: a see-through laboratory jar, a bendable drinking straw, a furnace lining. Give the property for each.
Answer
Jar: glass, because it is transparent and does not react with most chemicals. Straw: polymer, because it is light and bends without breaking. Furnace lining: ceramic, because it resists very high temperatures.
Question 3 (2 marks). A student says, “Ceramic plates are weak because they shatter when dropped.” Correct the statement.
Answer
Ceramic is hard but brittle. Brittle means it breaks instead of bending when struck. Shattering shows brittleness, not weakness.
Question 4 (3 marks). A part needs 200 cm³ of aluminium alloy, with a density of 2.7 g/cm³. Find its mass.
Answer
Mass = density × volume = 2.7 g/cm³ × 200 cm³ = 540 g.
Check: 2.7 × 2 = 5.4, so 2.7 × 200 = 540.
Question 5 (3 marks). A school needs 12 m of tubing.
Polymer tubing costs RM4.50 per metre. Metal tubing costs RM9 per metre. Find the cost of each and the difference.
Answer
Polymer: 12 × RM4.50 = RM54. Metal: 12 × RM9 = RM108. Difference = RM108 − RM54 = RM54.
Question 6 (2 marks). Explain why a polymer can be used to make a toy with a complicated shape.
Answer
A polymer softens when heated, so it can be melted and poured into a mould of the shape. It sets into that shape when it cools.
Question 7 (4 marks). An aluminium recycling plant receives 200 kg of scrap cans. The coating burns off as 10 kg of gas and ash, and 190 kg of metal is cast into ingots. Calculate the yield of ingots and state one assumption.
Answer
Check the balance: 10 + 190 = 200 kg. Yield = 190 ÷ 200 × 100 = 95%.
Assumption: the ingots are the only useful product, and no metal remains in the furnace.
Question 8 (4 marks). A hardness test gives these dent diameters using the same ball and force: pure iron 3.2 mm, iron with 1% carbon 2.0 mm, iron with 3% carbon 1.6 mm. State a conclusion and one assumption.
Answer
Conclusion: in these samples, adding carbon made the iron harder, because the dent got smaller from 3.2 mm to 2.0 mm to 1.6 mm as the carbon increased. Carbon atoms disturb the layers of iron atoms.
Assumption: the same ball, force and sample thickness were used for all three samples.
If you got these wrong
For questions 1 and 8, revisit explaining alloy properties. For 2 and 3, see comparing polymers, glass and ceramics. For 4 to 6, go to relating manufacturing choices to material properties. For 7, see interpreting industrial-process diagrams.
To have a teacher go through your wording, see online one-to-one Science tuition.