Write chemical reactions to affect the following transformations:
$(i)$ Butan$-1-$ol to butanoic acid
$(ii)$ Benzyl alcohol to phenylethanoic acid
$(iii)$ $3-$Nitrobromobenzene to $3-$nitrobenzoic acid
$(iv)$ $4-$Methylacetophenone to benzene$-1,4-$dicarboxylic acid
$(v)$ Cyclohexene to hexane$-1,6-$dioic acid
$(vi)$ Butanal to butanoic acid.

(A) $(i)$ $CH_3CH_2CH_2CH_2OH \xrightarrow{CrO_3 - H_2SO_4 (Jones \ reagent)} CH_3CH_2CH_2COOH$
$(ii)$ $C_6H_5CH_2OH$ $\xrightarrow{HBr} C_6H_5CH_2Br$ $\xrightarrow{KCN} C_6H_5CH_2CN$ $\xrightarrow{H_3O^{+}, \Delta} C_6H_5CH_2COOH$
$(iii)$ $C_6H_4(NO_2)Br$ $\xrightarrow{Mg, \text{ether}} C_6H_4(NO_2)MgBr$ $\xrightarrow{CO_2} C_6H_4(NO_2)COOMgBr$ $\xrightarrow{H_3O^{+}} C_6H_4(NO_2)COOH$
$(iv)$ $CH_3-C_6H_4-COCH_3$ $\xrightarrow{KMnO_4/KOH} KOOC-C_6H_4-COOK$ $\xrightarrow{dil. H_2SO_4} HOOC-C_6H_4-COOH$
$(v)$ $C_6H_{10} \xrightarrow{KMnO_4-H_2SO_4, \Delta} HOOC-(CH_2)_4-COOH$
$(vi)$ $CH_3CH_2CH_2CHO \xrightarrow{[O] \text{ or } \text{Tollens' reagent}} CH_3CH_2CH_2COOH$