Asample of cold water was mixed with a sample of hot water inside a calorimeter, and the final temperature of the cold water was 40 °c. which statement is true
about the hot water in the calorimeter?
it absorbed 40 joules.
it absorbed 80 joules
its final temperature was 80 °c.
its final temperature was 40 °c.

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.)