Explanation

(b)
Ziegler-Natta catalyst is an organometallic compound containing titanium. It is ${TiCl}_{4}$ and $\left( C_{2}H_{5} \right)_{3}$ Al. It is used in the preparation of polyethylene.
$nCH_{2} = CH_{2}\underset{{TiCl}_{4} + \left( C_{2}H_{5} \right)_{3}Al}{\overset{330 - 350\ K,\ 1 - 2\ atm}{\rightarrow}}\left( - CH_{2} - CH_{2} - \right)_{n}$
polyethylene