What is Freon-$12$?

State the various uses of:
$(i)$ Dichloromethane (Methylene chloride)
$(ii)$ Trichloromethane (Chloroform)
$(iii)$ Tri-iodomethane (Iodoform)
$(iv)$ Tetrachloromethane (Carbon tetrachloride)
$(v)$ Freons

Some halogen-containing compounds are useful in daily life. Some compounds of this class are responsible for the exposure of flora and fauna to increasing amounts of $UV$ light,which causes significant destruction. Name the class of these halocompounds. In your opinion,what should be done to minimize the harmful effects of these compounds?

Chloral $+$ Chlorobenzene $\xrightarrow{\text{Conc. } H_2SO_4}$ product.
The product is :

Silver halides are used in photography because

State the uses of halogen-containing organic compounds.