An atom is a small building block that forms matter. many different models of an atom have been made over the years. which of the following is not a reason why so many models of the atom have been made?
a
the atom has changed over the years.

b
new information led to new explanations.

c
scientists questioned each other's work.

d
new equipment allowed for new discoveries

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.)