When two hydrogen atoms combine with one oxygen atom, the result is a water molecule, which is a(n):

• A. isotope
• B. mixture
• C. compound
• D. element

Answer: (C)

Verified step by step guidance

1. Understand the definitions of the terms: an element is a pure substance made of only one type of atom; an isotope is a variant of an element with a different number of neutrons; a mixture is a physical combination of two or more substances; a compound is a substance formed when two or more different elements chemically bond together.
2. Recognize that hydrogen and oxygen are different elements, each consisting of only one type of atom.
3. When two hydrogen atoms chemically bond with one oxygen atom, they form a new substance with different properties from the individual elements.
4. Since this new substance consists of different elements chemically combined in a fixed ratio, it fits the definition of a compound.
5. Therefore, the water molecule formed by combining hydrogen and oxygen atoms is classified as a compound.