How many molecules of oxygen gas are in 1.42 moles of oxygen gas ?

You have 1.42mol O2.

If 1mol is 6.022*1023 molecules of O2, then 1.42mol O2 is equal to 1.42*6.022*1023 molecules of O2. This gives a total of approx. 8.55*1023 molecules of oxygen gas.

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.