Which of the following is an example of a compound? Group of answer choices

H2

O

H2O

Na

H2O is a compound because its a main constitute of earths hydrosphere

answer; i believe that the correct answer is (a) potassium(k)

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.