Why are most chemical changes difficult to reverse?

• A. Because chemical changes are temporary and easily undone.
• B. Because chemical changes only involve changes in physical state, not composition.
• C. Because chemical changes do not require energy to occur.
• D. Because chemical changes result in the formation of new substances with different chemical properties.

Answer: (D)

Verified step by step guidance

1. Understand that a chemical change involves the breaking and forming of chemical bonds, resulting in new substances with different chemical properties from the original substances.
2. Recognize that because new substances are formed, reversing the change requires breaking these new bonds and reforming the original substances, which often involves complex processes.
3. Note that physical changes, in contrast, only affect the state or appearance of a substance without altering its chemical composition, making them easier to reverse.
4. Realize that the energy required to reverse a chemical change can be significant, as it must overcome the stability of the new substances formed.
5. Conclude that most chemical changes are difficult to reverse because they involve the creation of new substances with different chemical properties, not just temporary or physical changes.