How have safety concerns about chemicals changed over time? A. Government officials rather than scientists decide what chemicals

are dangerous.

B. All nations have agreed to a set of safety standards, so testing

chemicals is no longer necessary.

C. As scientists have learned more about chemicals, they have

become more aware of their dangers.

D. Scientists are no longer as concerned about chemicals because

they are much safer today.

C. As scientists have learned more about chemicals, they have  become more aware of their dangers

Explanation:

Chemicals are substances with standard compositions, held together by chemical bonds. Chemicals can exist in different phases such as solid, liquid, and gaseous phases. Over time, with a growing understanding of chemicals, their composition, and their reaction methods, scientists now have a better knowledge of the dangers chemicals can pose. To that effect, they have created standard safety measures for those who have to work with these chemicals.

When these guidelines are strictly adhered to, the chances of suffering accidents, burns, and explosions with these chemicals are significantly reduced.

c is the answer because when something is left after something evaporates that shows the chemical change.

sry but any answer choices