Which of the following is the correct description of polypropylene?

Which of the following polymers is obtained from $C_2F_4$?

The correct statement regarding $X$ and $Y$ in the following set of reactions is:
$nCH_2=CH_2 \xrightarrow[(C_2H_5)_3Al, TiCl_4]{333-343 \ K, 6-7 \ atm} Y$
$nCH_2=CH_2 \xrightarrow[(C_6H_5COO)_2]{350-570 \ K, 1000-2000 \ atm} X$

Which compound/set of compounds is used in the manufacture of nylon $-66$ ?

Identify the catalyst used in the manufacturing of $HDP$.

The initiator used in cationic polymerization is........