Write down the preparation and use of Buna-$N$.

(N/A) Preparation: Buna-$N$ is obtained by the copolymerization of $1,3-$butadiene and acrylonitrile in the presence of a peroxide catalyst.
The reaction is as follows:
$nCH_2=CH-CH=CH_2 + nCH_2=CH(CN) \xrightarrow{\text{Copolymerization}} [-CH_2-CH=CH-CH_2-CH_2-CH(CN)-]_n$
Uses: It is resistant to the action of petrol,lubricating oil,and organic solvents and is used in making oil seals,tank lining,etc.