Question

an element: a contains only one type of atom b is always a solid c can be broken down into simpler substances d contains two or more different atoms

Explanation:

• Option A: By definition, an element is a pure substance that contains only one type of atom. For example, oxygen (O) is an element with only oxygen atoms, and gold (Au) has only gold atoms.
• Option B: Elements can exist in different states of matter. For instance, mercury (Hg) is an element that is liquid at room temperature, and oxygen (O₂) is a gas. So elements are not always solid.
• Option C: Elements are the simplest form of matter and cannot be broken down into simpler substances by chemical means. Compounds, on the other hand, can be broken down into elements.
• Option D: Elements contain only one type of atom, while compounds contain two or more different atoms. So this option describes a compound, not an element.

Answer:

A. Contains only one type of atom