In order to perform an experiment, a chemist needs an element that has similar properties of sodium (Na) but has a lower atomic mass. Which element should the chemist select for the experiment? A. Rubidium (Rb)
B. Potassium (K)
C. Lithium (Li)
D. Calcium (Ca)

Select the correct text in the passage. which sentences describe examples of sustainable living? i live in an old apartment building downtown, but my company is based in an office park on the outskirts of the city. i drive an old car that needs to be replaced. i plan to buy a hybrid for better gas mileage, but for now i am able to carpool with a couple of friends from work. the drive to the office park is about 45 minutes each way, but we do get to work in a modern building. the architects just received a leed certification for the design.

This chart lists four kinds of polymers and their sources. what can be known about all four polymers, despite their differences? they come from living things. they share ionic carbon bonds. they are at least 100 monomers long. they are made of repeating subunits.

What produces wave a)sound b) heats c)transfer of energy d)vibrations