Is freeze-drying a physical change or chemical change?

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.

Write two balanced equations 1. dissolving of solid sodium hydroxide in water 2. the reaction of sodium hydroxide solution with hydrochloric acid

The peak wavelength for the blackbody curve of a star is in the uv range. assuming the radiation from this star can reach earth, would you be able to see it?