The volume of a given quantity of a gas must increase if:
a the temperature and pressure increase
b the temperature and pressure decrease
c the temperature increases and the pressure decreases
d the temperature decreases and the pressure increases

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.)

State one important difference between a physical change and a chemical change?

Which of the following is a physical property flammability heat of combustion solubility and toxicity