Which of the following is the best definition of a physical change? A. Something that can be observed or measured while changing the identity of the substance.

B. A nail rusting.

C. A change that occurs without changing the identity of the substance.

D. Ice melting into water.

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.

If i make a solution by adding 83grams of sodium hydroxide to 750ml i’d water what is the molarity of sodium hydroxide

Need on both questionswill markbr />