b
(b)\(2\mathop {KI}\limits^{\,\, - 1} + 2CuS{O_4} \to {\mathop I\limits^{\rm{O}} _2} + C{u_2}{I_2} + 2{K_2}S{O_4}\) \({\mathop I\limits^{\rm{O}} _2} + 2N{a_2}\mathop {{S_2}}\limits^{ + 2} {O_3} \to \mathop {N{a_2}}\limits^{ + 2.5} {S_4}{O_6} + \mathop {2NaI}\limits^{\,\,\,\,\, - 1} \)