At what times is the ball 29.4 meters high going up and going down?

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.

Flourine is found to undergo 10% radioactivity decay in 366 minutes determine its halflife

0.09 moles of sodium sulfate in 12 ml of solution