When iron is exposed to oxygen and moisture, it undergoes oxidation, forming iron oxide—commonly known as rust. This process happens gradually; a new car might show no rust for years, while the same car left with scratched paint in a humid climate might rust within months. Salt accelerates the reaction, which is why coastal vehicles deteriorate faster.
It can be inferred from the text that
iron cannot rust without salt present
all cars rust at the same rate regardless of environment
scratched paint has no effect on rusting
environmental conditions significantly affect the rate of chemical reactions
Correct Answer: D
Choice D is the best answer. Different conditions cause dramatically different rusting rates.
- Context clues: Same car rusts differently based on paint condition, humidity, and salt exposure.
- Meaning: The varied rates show environment strongly influences chemical processes.
- Verify: Coastal vehicles deteriorating faster confirms environmental impact.
💡 Strategy: When the same process occurs at different rates under different conditions, infer environmental influence.
Choice A is incorrect because rust forms with just oxygen and moisture—salt accelerates it. Choice B is incorrect because rate varies with environment. Choice C is incorrect because scratched paint leads to faster rusting.