Question 8 Which of the following is not a pure substance? For Teacher Use Only NONEDOK1.423000 M1.L3Q3 compound element mixture molecule Question 9 2

## Step 1:Pure substances are made up of only one kind of particle and have fixed properties. They can be divided into compounds, elements, and molecules. All these options reflect inherently homogeneous characteristics:## Step 2:### An element is a material that consists of a single type of atom. For instance, copper and aluminum are examples of elements.## Step 3:### A compound is a molecule made up of two or more elements. For example, water ( ) is a compound because it is made up of hydrogen ( ) and oxygen ( ).## Step 4:### A molecule is a group of two or more atoms that are chemically bonded together. For example, a molecule of oxygen ( ) is composed of two oxygen atoms.## Step 5:The third option, however, is "mixture". A mixture comprises two or more different substances that are mixed but not combined chemically. Mixtures can vary in composition and properties, and the components maintain their original properties. Also, the components can usually be separated from one another by physical means. So a mixture is not a pure substance.#