The work of which scientist was most essential to the use of radioactive isotopes in medicine?
A. Antoine-Laurent Lavoisier
B. Robert Boyle
C. Marie Curie
D. John Dalton

Draw the skeletal structures of two different molecules that are each made of 5 carbon atoms and 12 hydrogen atoms.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

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.