Which of the following is a sign that a chemical product is expired?

A change in color or consistency is indeed a strong indicator that a chemical product may be expired. Over time, chemical formulations can break down and alter in their physical properties due to exposure to light, heat, and air, leading to significant changes in color and texture. For instance, a lotion that was once thick may become watery, or a hair color that was once vibrant might fade or darken unexpectedly. These changes suggest that the product is no longer stable or effective, which can impact its safety and results when used.

While changes in fragrance and an increase in viscosity can also indicate expiration, they may not be as definitive as a change in color or consistency in many cases. Additionally, a decreased price typically relates to promotions or sales rather than the state of the product.