2. How many copper atoms and how many of CuCl2?
A
one copper atom, one chlorine atom
B. one copper atom, two chlorine atoms
c. two copper atoms, one chlorine atom

Water's surface tension and heat storage capacity are accounted for by its a) orbitals b) weight c) hydrogen bonds d) mass e) size

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.)

What does a numerical subscript following an element in a chemical formula mean?