In the past,which of the following substances was commonly used as a solvent for dry cleaning of clothes?

Write the uses of $Freon$.

Give the uses of Freon-$12$,$DDT$,carbon tetrachloride,and iodoform.

Silver halides are used in photography because

State the uses and harmful effects (side effects) of dichloromethane (methylene dichloride),$CH_2Cl_2$.

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?