What’s earth atmosphere contains the element oxygen into different forms. The chemical formula for oxygen gas is O2 the Chemical formula for Ozone gas is O3 how do the structure of oxygen gas differ from that ozone?

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?