Which of the following describes a physical change?

• A. Change that results in a new substance
• B. Change in appearance only
• C. Change in chemical properties
• D. Change induced by heat reaction

Answer: (B)

A physical change is best described as a change in appearance only, without altering the substance's chemical properties. This encompasses changes like bending, breaking, freezing, or dissolving. During a physical change, the molecular structure of the substance remains the same; therefore, no new substance is formed.

For instance, when ice melts to water, it changes its state, but both ice and water are composed of H2O molecules. This highlights that while the form and appearance have changed, the intrinsic characteristics of the material remain constant.

In contrast, the other options represent different types of changes. When a change results in a new substance, such as burning wood to create ash and gas, it is indicative of a chemical change. A change in chemical properties involves alterations at the molecular level, leading to different chemical behavior, again indicative of a chemical transformation. Lastly, changes induced by heat typically involve chemical reactions, which would often lead to the formation of new substances, thus aligning with the definition of a chemical change rather than a physical one.