When Joe has worked out the density of each piece of rock, what can be do with his results to find out if there is a relationship?

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

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

Some liquids can be distilled, but only at temperatures that are so high that it is impractical, or so high the compound decomposes. explain why distillation such compounds at significantly less than atmospheric pressure (some degree of vacuum) would solve this problem.