Answer
Yes — if it exists in more than one physical phase at once.
Work Step by Step
Pure water (H₂O) is a substance, meaning its composition is uniform and fixed.
However, heterogeneous mixture means non-uniform composition or more than one phase present.
Examples:
- Ice and liquid water together: Even if both are pure H₂O, the mixture of solid and liquid phases is heterogeneous because the phases are visibly distinct.
- Steam and liquid water: In boiling water, vapor bubbles coexist with liquid water — again, a heterogeneous mixture of phases.
In conclusion, a sample of pure water can exist as a heterogeneous mixture when it contains more than one physical phase, despite being chemically uniform.
