Which is the correct definition of density? weight
volume
mass. volume
mass
volume
volume
weight

Consider the balanced equation below. n2h4 + 2h2o2 n2 + 4h2o what are the mole ratios of hydrazine (n2h4) to hydrogen peroxide (h2o2) and hydrazine to water? 1: 2 and 1: 4 1: 3 and 1: 4 1: 2 and 3: 5 1: 3 and 3: 5

How many atoms of mg are present in 97.22 grams of mg? 6.022 × 1023 2.408 × 1024 4.818 × 1024 5.855 × 1025

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.)