3. A helium laser emits light with a wavelength of 6.33 x 10^-7m. What is the frequency of the light? *
2.11 X10^15 Hz
O 4.74 x 10^14 Hz
O 18.99 Hz
N

An atom of lithium-7 has an equal number of(1) electrons and neutrons(2) electrons and protons(3) positrons and neutrons(4) positrons and protons

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.)

An atom's configuration based on its number of electrons ends at 3p4. another atom has seven more electrons. starting at 3p, what is the remaining configuration? 3p63d34s2 3p43d54s2 3p64s23d3 3p44s23d