The freons are colourless, odourless, and extremely stable. The presence of Group 17 elements such as fluorine, chlorine, and other such elements contributes to their stability. The molecule is extremely stable due to the presence of C-F and C-H bonds. However, in the presence of ultraviolet rays in the stratosphere, freons die out due to UV ray exposure. There are over 300 different types of freon gases.