c
\({\mathop {Na_2}\limits^{ + 1} }\mathop O\limits^{ - 2} \,\, + \,\,\,{\mathop {H_2}\limits^{ + 1} }\mathop S\limits^{ + 6} {\mathop {O_4}\limits^{ - 2} }\,\,\,\, \to \,\,\,\,{\mathop {Na_2}\limits^{ + 1} }\mathop S\limits^{ + 6} {\mathop {O_4}\limits^{ - 2} }\,\, + \,\,\,{\mathop {H_2}\limits^{ + 1} }\mathop O\limits^{ - 2} \)