A) caco3- cao- cac2- c2h2- C6H6 - C6H5CL- C6H5ONa- C6H5OH- C6H2Br3OH

\(\begin{array}{l}
CaC{O_3} \to CaO + C{O_2}\\
2CaO + 5C \to 2Ca{C_2} + C{O_2}\\
Ca{C_2} + 2{H_2}O \to Ca{(OH)_2} + {C_2}{H_2}\\
3{C_2}{H_2} \to {C_6}{H_6}\\
{C_6}{H_6} + C{l_2} \to {C_6}{H_5}Cl + HCl\\
{C_6}{H_5}Cl + NaOH \to {C_6}{H_5}ONa + HCl\\
{C_6}{H_5}ONa + C{O_2} + {H_2}O \to {C_6}{H_5}OH + NaHC{O_3}\\
{C_6}{H_5}OH + 3B{r_2} \to {C_6}{H_2}B{r_3}OH + 3HBr
\end{array}\)