SOMEONE PLEASE HELP ME OUTT PLSS

Write the chemical symbols for three different atoms or atomic cations with 27 electrons. asap!

In the millikan oil drop experiment they determined that every drop had a charge which was a while number multiple of -1.60x10^-19. if a drop has a total charge of -9.60x10^-19 then how many excess electrons are contained within the drop?

Which of the following has wavelength longer than the wavelength of viable light? a) x rays b) gamma rays c) radios waves d) ultraviolet waves