A liquid changes color as it cools and becomes solid. How can you confirm

the type of change that took place?

It's a physical change. Instantly we know if a liquid could turn solid, then it could turn back into liquid and so on. That is because it's malleable. Meaning that it's previous texture wouldn't change whether if we wanted to freeze it or not. However the temperature would have an affect on the concentration and the pH of the water depending on its ionization and oxidation levels.