ઉપરોક્ત પ્રક્રિયા કઇ પરીસ્થિતીમા થાય છે ?

$(1)$ $\begin{matrix}
   O  \\
   ||  \\
   {{C}_{6}}{{H}_{5}}-C-{{C}_{6}}{{H}_{5}}  \\
\end{matrix}$

$(2)$ $C _{6} H _{5}- CHO$

$(3)$ $p - CH _{3}- C _{6} H _{4}- CHO$

$(4)$ $p - CH _{3} O - C _{6} H _{4}- CHO$

$\mathop {\begin{array}{*{20}{c}}
  {OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,O} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,||} \\ 
  {C{H_2} = C - C{H_2} - C - C{H_3}} 
\end{array}}\limits_{(I)}  \rightleftharpoons $

$\mathop {\begin{array}{*{20}{c}}
  {OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,O} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,||} \\ 
  {C{H_3} - C - C{H_2} - C - C{H_3}} 
\end{array}}\limits_{(II)}  \rightleftharpoons $

$\mathop {\begin{array}{*{20}{c}}
  {OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,O} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,||} \\ 
  {C{H_3} - C = CH - C - C{H_3}} 
\end{array}}\limits_{(III)} $

$\mathop {(A)}\limits_{ gives\,\,positive ~\\ iodoform\,Test }  \xrightarrow[\begin{subarray}{l} (ii)\,{H^ + },{H_2}O +  ~\\ (iii)\,conc.\,{H_2}S{O_4}/\Delta \end{subarray} ]{{{\text{(i) C}}{{\text{H}}_{\text{3}}}{\text{MgBr}}}}(B)\xrightarrow{{{O_3}/Zn,{H_2}O}}$