Final answer:
The interaction of water, salt, and air with the exterior of cars is a combination of both mechanical and chemical processes, with examples like abrasion being mechanical and rust formation being a chemical reaction.
Step-by-step explanation:
The action of water, salt, and air on the outside of cars involves both mechanical and chemical processes. Mechanical weathering includes the physical breakdown of materials without changing their chemical composition, such as when salt particles blown against a car's surface cause abrasion. On the other hand, chemical weathering is when the car's materials undergo chemical reactions, such as oxidation, where the iron in the car's body reacts with oxygen in the presence of water and salt to form rust.
In the context of the provided exercises, for example, a bicycle rusting (Exercise 7.2.1) is a chemical reaction similar to rust forming on a car. An iron nail corroded in moist air is another example of a chemical change that relates to the chemical weathering of a car's exterior (Exercise 3.6.1). Condensation of steam is considered a physical change, whereas the burning of gasoline is a chemical change (Example 1.1.1), highlighting the differences between chemical and physical changes that can occur in various contexts.