At which condition will the entropy of a pure solid be zero? a. when a substance is at absolute zero b. when a substance is undergoing a phase change c. when a substance is in its elemental form d. when the temperature is 0ºc

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 periodic tablewarm-upuse the periodic table in the tools bar to answer the following questions.what elemental classification does oxygen belongto? done

Fossil fuels are organic compounds that are made from