1. Which of the following is the BEST evidence that rusting is a chemical property rather than a physical property of iron?
Rust can form on any iron.
Rust forms slowly.
Rust cannot turn back into iron.
Rust does not look the same as iron.

C. Rust cannot turn back into iron

Explanation:

One of the unique characteristics of chemical change or processes is that, when a substance undergoes this process, the process is irreversible. It cannot be easily reversed. The new compound or substance is often fundamentally different from the original substance before the change occurs.

The best evidence that shows that rusting is more of a chemical property of iron, is that, rusting cannot turn back to iron. The change is irreversible.