What effect does observing a substance's physical properties have on the substance?

There is no effect. When you observe a substance's physical properties, you're not doing anything that would catalyze a chemical change. For example, you most often observe with your eyes, and/or, if safe, you waft the substance's smell to your nose. Neither of these observations will effect the substance's physical properties.

Idont know. if you want an answer you need to give us some context dude.