Question

which is a substance that is made up of only one type of atom? element solution mixture compound

Explanation:

To determine the substance made of only one type of atom, we analyze each option:

• Element: By definition, an element consists of only one type of atom (e.g., hydrogen has only H atoms, oxygen has only O atoms).
• Solution: A solution is a homogeneous mixture of two or more substances (e.g., salt water has H₂O and NaCl particles), so it has multiple types of atoms or molecules.
• Mixture: A mixture contains two or more different substances (elements or compounds) physically combined, so it has multiple types of atoms/molecules.
• Compound: A compound is made of two or more different types of atoms chemically bonded (e.g., H₂O has H and O atoms), so it has multiple atom types.

Thus, the element is the substance with only one type of atom.

Answer:

A. element