How might a firefighter use chemistry? A. Chemistry can help a firefighter plan an escape route through a
burning building
B. Chemistry can help a firefighter understand combustion and how
to put out fires.
C. Chemistry can help a firefighter understand how much of a load
the floors of a burning building can hold,
D. Chemistry can help a firefighter plan an exercise routine to prepare
for fires

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.)

Using the first volume and temperature reading on the table as v1 and t1, solve for the unknown values in the table below. remember to use the rules of significant figures when entering your numeric response.

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?