Materials of the modern world：練習問題

When crude oil is processed in a fractional distillation tower, different fractions are collected at different heights. Which statement correctly identifies the properties of the fraction collected at the topmost part of the tower?

A construction company chooses Polyvinyl Chloride (PVC) for water pipes instead of Polyethylene (PE). Which of the following is the most likely scientific reason for this choice based on the concept of form and function?

During the industrial extraction of iron from its ore, the ore is heated in a furnace with carbon. What is the main scientific purpose of including carbon in this reaction?

When classifying materials from crude oil, a student finds a substance that is a solid at room temperature and very difficult to ignite. Which of the following is most likely true about this substance compared to a liquid fraction like gasoline?

Which of the following best describes the chemical nature of alloys compared to pure metals?

In a crude oil refinery, the mixture of hydrocarbons is separated using fractional distillation. Which physical property of the different hydrocarbon molecules is the primary basis for this separation technique?

In a fractionating tower, explain why refinery gas is collected at the top while bitumen remains at the bottom, referring to the temperature gradient.

Explain, in terms of atomic arrangement, why adding a small amount of carbon to iron to make steel makes the material much harder than pure iron.

Modern materials like plastics have significantly changed our lifestyles since their invention.

(a) Plastics are described as macromolecules. Explain what this term means in relation to how plastics are formed from smaller hydrocarbon molecules. (1 point)
(b) Provide one example of a common plastic (e.g., PE or PVC) and state one specific everyday use for it. (2 points)
(c) State one advantage of using plastic rather than glass for manufacturing portable water bottles. (1 point)

Pure metals are frequently converted into alloys to make them more suitable for specific industrial and domestic applications.

(a) Define the term alloy and explain the general process of how it is made from a pure metal. (2 points)
(b) Stainless steel is an alloy of iron. Identify one element added to iron to create stainless steel and state one property that makes this alloy superior to pure iron for making kitchen sinks. (2 points)
(c) Explain why an alloy is generally harder than its constituent pure metal by referring to the arrangement of its atoms. (1 point)