A student trying to determine if a liquid was a mixture or a pure substance made several following observations. Which observation would best support the conclusion that the liquid was a mixture?

Question

When attached to a circuit, the liquid conducted electricity.

When the liquid evaporated, a white residue remained.

The liquid has a density of 1.28 g/ml.

The liquid allowed light to pass through it easily

Answer 1

The observation that would best support the conclusion that the liquid was a mixture is:

When the liquid evaporated, a white residue remained.

This observation suggests the presence of multiple components in the liquid, as a pure substance would not leave residue upon evaporation. In a mixture, different substances can have different boiling points; when the liquid evaporates, one component may leave a solid residue behind.