Which process changes the identity of a substance?

Which process changes the identity of a substance?

• A. Physical change
• B. Chemical change
• C. Conservation of mass
• D. Atom

Answer: (B)

A chemical change is when a substance’s identity changes because new bonds form and different substances are produced. This means the material you started with is transformed into something with a different composition and properties, such as color, odor, or energy released. For example, burning wood turns it into ash, smoke, and gases—the original wood molecules have been chemically altered into new substances. In contrast, physical changes only change form or state without creating a new substance, like ice melting into water or metal being cut into pieces—the substance remains the same material at the molecular level. The other options describe ideas or concepts that aren’t processes that change what something is, such as a principle about matter or a basic unit of matter.

A chemical change is when a substance’s identity changes because new bonds form and different substances are produced. This means the material you started with is transformed into something with a different composition and properties, such as color, odor, or energy released. For example, burning wood turns it into ash, smoke, and gases—the original wood molecules have been chemically altered into new substances. In contrast, physical changes only change form or state without creating a new substance, like ice melting into water or metal being cut into pieces—the substance remains the same material at the molecular level. The other options describe ideas or concepts that aren’t processes that change what something is, such as a principle about matter or a basic unit of matter.