HAZMAT Technician Practice Exam

In terms of physical changes, which of the following is true?

1. Physical changes alter the chemical composition of substances

2. Physical changes can be reversed

3. Physical changes release more energy than chemical changes

4. Physical changes do not involve changes in state

The correct answer is: Physical changes can be reversed

Physical changes are processes that alter the form or appearance of a substance without changing its chemical composition. This characteristic allows many physical changes to be reversible, meaning the original substance can be recovered after the change occurs. For instance, when water is frozen into ice, it can be melted back into water, demonstrating the reversible nature of this physical change. In contrast, the other statements do not accurately reflect the nature of physical changes. They might imply that physical changes involve alterations in chemical structures or that they release energy to a greater extent than chemical changes, neither of which holds true. Understanding the reversible nature of physical changes is essential for properly applying concepts in chemistry and hazardous materials handling.