Final answer:
An element is a substance that cannot be broken down into a more simple substance. Examples of elements include mercury.
Step-by-step explanation:
The substance that cannot be broken down into a more simple substance is called an element. An element is a pure substance that consists of only one type of atom and cannot be broken down further by chemical means. It is denoted by a symbol and has unique physical and chemical properties.
For example, mercury is an element because it is made up of only mercury atoms and cannot be separated into simpler substances. On the other hand, white wine, ranch-style salad dressing, and table sugar (sucrose) are all mixtures composed of multiple substances and can be broken down into simpler components.