Final answer:
Among the given options, a) drying of wet clothes, b) sublimation, and c) melting of wax are physical changes, because the original substance remains the same before and after the change. The rusting of iron (option d) is not a physical change, but a chemical one, because iron transforms into rust.
Step-by-step explanation:
The question asks which of the following is not a physical change. A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. The original substance is the same before and after the change; only its form has altered. For example, when wax melts, it still remains wax, and when wet clothes dry, they are still the same clothes. In these cases, a) drying of wet clothes, b) sublimation, and c) melting of wax, they are all examples of physical changes.
However, d) rusting of iron is not a physical change, but a chemical one. In this process, iron reacts with oxygen in the presence of moisture to form a new substance, which we commonly call rust. The original iron is transformed into another substance.
Learn more about physical and chemical changes