Potassium has an atomic number of 19.
which of a potassium atom's electrons are its valence electrons?
select one:
a. those in the third shell from the nucleus.
b. those in the second shell from the nucleus.
c. those in the outermost shell.
d. those in the innermost shell.

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.

its first and third is your answer i did the qustion the fourth isnt right