Final answer:
To identify a chemical substance, you can use different properties and changes such as comparing properties to a known substance, using properties to determine separation techniques, and creating classifications based on properties and changes.
Step-by-step explanation:
To identify a chemical substance, you can use different properties and changes. Firstly, specific pure substances have their own unique properties, so you can compare the properties of an unknown substance to a known one to see if they are the same or different. Secondly, when separating mixtures, you can use their properties to determine what separation technique is needed. And finally, different substances will have different properties and will change in different ways, so you can create classifications of substances based on their properties and/or changes.