Which statement correctly describes the differences between an element, a compound, and a mixture, and gives a typical example for each?

Which statement correctly describes the differences between an element, a compound, and a mixture, and gives a typical example for each?

• A. Element is a pure substance made of one type of atom; water is an element.
• B. Compound is two or more elements chemically bonded; air is a pure substance.
• C. Mixture is not chemically bonded and can be separated by physical means (air).
• D. All three are elements.

Answer: (C)

The main idea here is how substances are built and kept apart. An element is a pure substance made of only one type of atom. A compound is formed when two or more elements bond chemically to form a new substance. A mixture is simply a combination of substances that are not chemically bonded to each other, so the components can be separated by physical means. This statement correctly describes a mixture: it is not chemically bonded and can be separated by physical methods, with air as a typical example. Air is a blend of gases like nitrogen and oxygen, none of which are bonded into a new substance, so you can separate them by physical processes. To place it in context, think of common examples: an element such as oxygen gas is just a single kind of atom pair; a compound like water consists of hydrogen and oxygen bonded together; a mixture like air or salad dressing with oil and vinegar shows components that keep their own properties and can be separated without breaking chemical bonds. The other statements mix up these ideas—water isn’t an element, air isn’t a pure substance, and a compound isn’t simply a mix of elements without bonding.

The main idea here is how substances are built and kept apart. An element is a pure substance made of only one type of atom. A compound is formed when two or more elements bond chemically to form a new substance. A mixture is simply a combination of substances that are not chemically bonded to each other, so the components can be separated by physical means.

This statement correctly describes a mixture: it is not chemically bonded and can be separated by physical methods, with air as a typical example. Air is a blend of gases like nitrogen and oxygen, none of which are bonded into a new substance, so you can separate them by physical processes.

To place it in context, think of common examples: an element such as oxygen gas is just a single kind of atom pair; a compound like water consists of hydrogen and oxygen bonded together; a mixture like air or salad dressing with oil and vinegar shows components that keep their own properties and can be separated without breaking chemical bonds. The other statements mix up these ideas—water isn’t an element, air isn’t a pure substance, and a compound isn’t simply a mix of elements without bonding.