Question

which of the following can be described as a molecule but not a compound? multiple choice mgcl₂ co₂ o₂ h₂o nacl

Explanation:

1. Recall definitions: A molecule is a group of atoms bonded together. A compound is a molecule made of at least two different elements.
2. Analyze each option:

• $\ce{MgCl2}$, $\ce{CO2}$, $\ce{H2O}$, $\ce{NaCl}$: All contain two or more different elements (e.g., $\ce{Mg}$ & $\ce{Cl}$ in $\ce{MgCl2}$), so they are compounds (and molecules, in most cases).
• $\ce{O2}$: Consists of only one element (oxygen) bonded as a molecule, so it is a molecule but not a compound.

Answer:

C. $\boldsymbol{O_2}$