What is the partial pressure of oxygen in a gas mixture that is 40% oxygen, 40% argon, and 20% helium, when the total pressure of the gas is 1,000 mm hg?

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.