What process involves grouping chemicals based on their physical properties?

The process that involves grouping chemicals based on their physical properties is classifying. Classification is a fundamental aspect of scientific inquiry, where substances are organized according to shared characteristics. In chemistry, this can include properties such as state of matter (solid, liquid, gas), density, melting and boiling points, solubility, and reactivity.

Observing is related to the act of noting and recording details about the samples but does not inherently involve grouping them. Measuring pertains to quantifying specific attributes like volume, mass, or concentration, but again, it doesn't involve the systematic organization of substances. Testing typically refers to conducting experiments to determine specific properties or behaviors of chemicals but does not focus on their classification based on physical properties.