2/

a/$CH_{3}COONa +NaOH \buildrel{{t^o,CaO}}\over\longrightarrow CH_{4}+Na_{2}CO_{3}$

$2CH_{4} \buildrel{{1500^oc,\text{làm lạnh nhanh}}}\over\longrightarrow C_{2}H_{2}+3H_{2}$

$C_{2}H_{2}+H_{2} \buildrel{{Pd,PbCO_{3}}}\over\longrightarrow C_{2}H_{4}$

$CH_{2}=CH_{2} \buildrel{{t^o,xt,p}}\over\longrightarrow -(CH_{2}-CH_{2})-_{n}$

b/

$Al_{4}C_{3}+12H_{2}O \to 4Al(OH)_{3}+3CH_{4}$

$2CH_{4} \buildrel{{1500^oc,\text{làm lạnh nhanh}}}\over\longrightarrow C_{2}H_{2}+3H_{2}$

$CH≡CH+HCl \buildrel{{HgCl_{2},150^oC-200^oC}}\over\longrightarrow CH_{2}=CH_Cl$

$CH_{2}=CHCl \buildrel{{t^o,p,xt}}\over\longrightarrow -(CH_{2}-CHCl)-_{n}$

c/

$2CH_{4} \buildrel{{1500^oc,\text{làm lạnh nhanh}}}\over\longrightarrow C_{2}H_{2}+3H_{2}$

$C_{2}H_{2}+H_{2}O \buildrel{{HgSO_{4},H_{2}SO_{4},80^oC}}\over\longrightarrow CH_{3}CHO$

$CH_{3}CHO+Br_{2}+H_{2} \to CH_{3}COOH+2HBr$

$CH_{3}COOH+Na \to CH_{3}COONa+1/2H_{2}$

3/

$Ankin:C_{n}H_{2n-2}$

$C_{n}H_{2n-2}+2Br_{2} \to C_{n}H_{2n-2}Br_{4}$

0,25                      0,5

$nBr_{2}=\frac{80}{160}=0,5$

$m_{\text{bình tăng}}=m_{\text{ankin phản ứng}}=8,6$

$M_{Ankin}=\frac{8,6}{0,25}=34,4$

⇒$14n-2=34,4⇔n=2,6$

⇒$C_{2}H_{2}$ và $C_{3}H_{4}$