Why was Becquerel's experiment a first step in discovering radioactivity? A. It showed that a substance could phosphoresce when it was not exposed to light.
B. It showed that the substance that was used by Becquerel could phosphoresce.
C. It showed that a substance could constantly emit radiation even if it was not exposed to light.
D. It showed that a substance emitted radiation when it was exposed to light.

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

In a chemical reaction at equilibrium, the rate of the forward reaction the rate of the reverse reaction. if the rate of the forward reaction more products are formed.

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.)