a)
(1) CH3-CH3 \(\xrightarrow{{{{500}^0}C,xt,p}}\) CH2=CH2 + H2
(2) CH2=CH2 \(\xrightarrow{{{t^0},p,xt\,}}\) ( -CH2-CH2-)n
b)
(1) 2CH4 \(\xrightarrow[{làm\,\operatorname{lạnh} \,nhanh}]{{{{1500}^0}C}}\) C2H2 + 3H2
(2) C2H2 \(\xrightarrow{{N{H_4}Cl,CuCl}}\) CH≡C-CH=CH2
(3) CH≡C-CH=CH2 + H2 \(\xrightarrow{{Pb,{t^0}}}\) CH2=CH-CH=CH2
(4) CH2=CH-CH=CH2 \(\xrightarrow{{{t^0},p,xt\,Na}}\) (-CH2-CH=CH-CH2-)n