Can someone help me? I’m stuck on this science question

How has the scientific community addressed the safety of chemicals? a. chemicals are repeatedly tested, even those that have existed for a long time. b. existing chemicals are tested if they have never been tested before. c. chemicals are tested if they are suspected to have caused a problem. d. only new chemicals are tested.

Substance x has a fixed volume, and the attraction between its particles is strong .substance y had widely spread out particles and can be compressed what can most likely be concluded about these substances

Which of the following would be an accurate picture of the earth during the summer time of the northern hemisphere?