Calculate how many molecules are present in the following quantities.

8.2 g of h2o
14.4 g of c6h8

In the analysis of hair and fiber samples, which does a compound comparison microscope allow for that a conventional compound microscope does not? a. simultaneous observation b. polarization c. fluorescence d. higher magnification

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

The atoms of a solid aluminum can are close together, vibrating in a rigid structure. if the can is warmed up on a hot plate, what happens to the atoms?