To determine which combination of atoms will form a molecule but not a compound, let's first recall the difference between a molecule and a compound:
- Molecule: A molecule is formed when two or more atoms are chemically bonded together.
- Compound: A compound is a type of molecule that consists of atoms of different elements. Therefore, if the molecule consists of atoms of the same element, it is not a compound.
Given the chart:
[tex]\[
\begin{tabular}{|c|c|}
\hline Atom & Element \\
\hline$W$ & oxygen \\
\hline$X$ & hydrogen \\
\hline$Y$ & carbon \\
\hline$Z$ & oxygen \\
\hline
\end{tabular}
\][/tex]
Let's examine each given combination:
1. [tex]$W$[/tex] and [tex]$X$[/tex]
- Elements: Oxygen (W) and Hydrogen (X)
- These are different elements, so this combination forms a compound.
2. [tex]$X$[/tex] and [tex]$Y$[/tex]
- Elements: Hydrogen (X) and Carbon (Y)
- These are different elements, so this combination forms a compound.
3. [tex]$W$[/tex] and [tex]$Z$[/tex]
- Elements: Oxygen (W) and Oxygen (Z)
- These are the same element, so this combination forms a molecule that is not a compound.
4. [tex]$Y$[/tex] and [tex]$Z$[/tex]
- Elements: Carbon (Y) and Oxygen (Z)
- These are different elements, so this combination forms a compound.
From this examination, we can see that the combination of atoms that will form a molecule, but not a compound, is:
[tex]\[
\boxed{W \text{ and } Z}
\][/tex]
