Among the species given below, the total number of diamagnetic species is $\_\_\_\_$ . H atom, $\mathrm{NO}_2$ monomer, $\mathrm{O}_2{ }^{-}$(superoxide), dimeric sulphur in vapour phase, $\mathrm{Mn}_3 \mathrm{O}_4,\left(\mathrm{NH}_4\right)_2\left[\mathrm{FeCl}_4\right],\left(\mathrm{NH}_4\right)_2\left[\mathrm{NiCl}_4\right], \mathrm{K}_2 \mathrm{MnO}_4, \mathrm{~K}_2 \mathrm{CrO}_4$