What statement best describes the molecules found in living systems?
a. they contain mostly sulfur, gold, and lead.
b. they are very simple molecules made of carbon and hydrogen
c. they are very complex molecules made mostly of carbon, hydrogen, and oxygen

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change?

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line

Chemistry worksheet - i am not sure what they are asking for exactly?