Which element do all organic molecules contain?
a. sulfur
b. carbon
c. oxygen
d. nitrogen

Which substances have the lowest melting points: ionic covalent, or metallic

The wave shown on the electromagnetic spectrum disturb the medium it passes through a)different frequency. b)the same frequency .

Which part of a feedback mechanism is able to monitor the conditions outside of cells and usually uses nerve cells to relay this information to an intergrating center