$1$$a)CaC_2\rightarrow C_2H_2\rightarrow CH_3CHO\rightarrow CH_3COOH$
$b)CH_3OH\rightarrow CH_3Cl\rightarrow C_2H_6\rightarrow C_2H_5Cl\rightarrow C_2H_5OH\rightarrow CH_3COOH$
$2$
$a)C_2H_5OH\rightarrow CH_3CHO\rightarrow CH_3COOH\rightarrow CH_3COOCH_3$
$b)\Delta \rightarrow CH_2Br-CH_2-CH_2Br\rightarrow HOCH_2CH_2CH_2OH\rightarrow OHCCH_2CHO$
$\rightarrow HOOCCH_2COOH$
$c)C_2H_6\rightarrow C_2H_5Br\rightarrow C_2H_5OH\rightarrow CH_3CHO\rightarrow CH_3COOH$