3. when someone refers to the "periods of the periodic table, what are they referring to?
a. the metalloids
b. the rows of the table
c. the different historical models of the table
d. the groups of elements with similar properties

Chemical energy is a form of energy. a. heat b. kinetic c. potential d. electromagnetic

Two forces produce equal torques on a door about the door hinge. the first force is applied at the midpoint of the door; the second force is applied at the doorknob. both forces are applied perpendicular to the door. which force has a greater magnitude?

What would be the radius of the earth if it had its actual mass but had the density of nuclei? express your answer to two significant figures and include the appropriate units.