Identifying unknown materials by looking at their physical properties can be tough because of a few reasons:

• Similarities: Many materials look or feel alike, which makes it hard to tell them apart.
• Mistakes in Measurement: If we don’t measure correctly, we can get the wrong idea about what the material is.
• Changing Conditions: Things like temperature and pressure can change how a material behaves, making identification tricky.

To make it easier to figure out what a material is, we can use special methods like spectroscopy or chromatography. These techniques help us see things more clearly. Working carefully during experiments also helps us be more accurate in identifying materials.