A sample of iodine is easiest to ship as a powder because it is , making it easy to break into small pieces.

Helium is less
than the elements that make up the air we breathe, so a balloon filled with helium will float in air.

Plastic is a compound of nonmetallic elements, so its
properties make it a popular coating for electric wires to prevent the current from escaping.

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)