Final answer:
The incorrect option is 'cannot be broken down into simpler substances' as compounds can be separated into their elemental components through chemical reactions. A compound is a substance made of two or more elements in a fixed proportion, which can undergo chemical changes, unlike an element that cannot be broken down chemically.
Step-by-step explanation:
The question asks us to identify which of the given options is not a characteristic of a compound. Among the options provided, option b, 'cannot be broken down into simpler substances' is incorrect because compounds can be broken down into simpler substances, namely the elements that compose them. This breakdown can only occur through chemical means, not physical means.
A compound is a pure substance that consists of two or more elements chemically combined in fixed proportions. It is distinct from an element in that it can be separated into the simpler substances that constitute it through chemical changes. Conversely, an element is a substance that cannot be broken down into simpler substances by chemical means and is composed of a single type of atom.
Some examples to illustrate these concepts include water (H₂O), which is a compound consisting of hydrogen and oxygen in a 2:1 ratio, and the periodic table, which lists all known elements based on their properties.