PRoblem 1: For which of the following activities might you want to hire a chemist?

A. building a garage

B. testing a sample of water from a well

C. finding a comet

D. examining the structure of plant cells
PRoblem 2: Which of the following procedures involves a physical change in one of the substances?

A. creating salt by reacting sodium metal and chlorine gas

B. allowing a nail to rust

C. building a model rocket propelled by mixing baking soda and vinegar

D. grinding chalk into a fine powder