b
(b) The enol form of acetone on treatment with \({D_2}O\) undergoes enolisation, deutration (addition of \({D_2}O\)) and dehydration (removal of \({H_2}O\)).

The repeated enolisation, deutration and dehydration ultimately gives \(C{D_3}\,.\,COC{D_3}\,({\rm{B}})\).

\(\mathop {C{H_3} - \mathop {\mathop C\limits^{||} }\limits^O  - C{H_3}}\limits_{{\text{Acetone}}\,{\text{(ketoform)}}} \)  \(\left[ {\mathop {C{H_3} - \mathop {\mathop {C\,\,}\limits^{|\,\,\,\,\,} }\limits^{OH}  = C{H_2}}\limits_{{\text{enol form}}} } \right]\) \(\leftrightharpoons \)

\(C{H_3} - \mathop {\mathop {{\text{ }}C}\limits^|  = }\limits^{OD\,\,\,} C{H_2}\)  \(\leftrightharpoons \) \(C{H_3} - \mathop {\mathop {C{\mkern 1mu} {\mkern 1mu} }\limits^{||{\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} } }\limits^{O\,}  - C{H_2}D\)   \(\leftrightharpoons \)

\(C{H_2} = \mathop {\mathop {C{\mkern 1mu} {\mkern 1mu} }\limits^{|{\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} } }\limits^{OH}  = C{H_2}D\) \(\overset {{D_2}O} \longleftrightarrow \) \(C{H_2} = \mathop {\mathop {C{\mkern 1mu} {\mkern 1mu} }\limits^{|{\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} } }\limits^{OD}  - C{H_2}D\)

\(DC{H_2} - \mathop {\mathop C\limits^{||} }\limits^O  - C{H_2}D\)   \(\leftrightharpoons \)   \({D_3}C - \mathop {\mathop C\limits^{||} }\limits^O  - C{D_3}\)