$S _{8( s )}+ a OH ^{-}_{( aq )} \rightarrow b S ^{2-}_{( aq )}+ c S _{2} O _{3}{ }^{2-}{ }_{( aq )}+ d H _{2} O _{(\ell)}$
$'a'$ નું મૂલ્ય ............ છે. (પૂર્ણાક જવાબ)
${H_2}\mathop S\limits^{ } {O_4}\,\,\,\,\, \to \,\,\,\,\,\mathop S\limits^{ } {O_2}$