some examples of chemical properties are toxicity and flammability
THE ANSWER IS chemical PROPERTIES
The properties of a substance which can be measured or observed without altering the identity of the substance must be physical properties.
For example if we are heating water sample from room temperature to higher temperature (below the boiling range) the water will get heat up however there will be no change in identity of the water.
In other cases like:
Chemical properties : there may be change in the identity of the substance as it may react with another substance to produce a new substance.
Reactive properties : they are again like chemical properties
phase properties : there are certain phase changes where the identity of substance gets changed. For example the rhombic sulfur changes to monoclinic sulfur.
The correct answer is physical properties and/or phase properties.
Chemical properties can alter the substance (if you burn wood, it becomes ash and is no longer wood).
Reactive properties are also chemically changing the substance.
Phase properties are where the element can be in solid, liquid, or gas form so these could also be an answer.