Explanation:
(b) \(\begin{array}{*{20}{c}}{\mathop {COOH}\limits_{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,} }\\{COOH}\end{array}\). \(2{H_2}O\) \( \to \;126\) is molecular wt.
\(\therefore {\rm{Equivalent}}\,\,{\rm{wt}}{\rm{.}} = {\rm{Molecular}}\,\,{\rm{wt}}\,{\rm{.}}/2 = 63\)