Total number of molecules/species from following which will be paramagnetic is ______.O₂,${\mathrm{O}}_2^{+}$,${\mathrm{O}}_2^{-}$, NO,NO₂, CO, K₂[NiCl₄],[Co(NH₃)₆]Cl₃, K₂[Ni(CN)₄]

${\mathrm{O}}_2\to 2 \text{unpaired electrons according to MOT}$
${{\mathrm{O}}_2}^{+}\to 1 \text{unpaired electrons according to MOT}$
${{\mathrm{O}}_2}^{-}\to 1 \text{unpaired electrons according to MOT}$
$\mathrm{NO}\to \text{odd electron species}$
${\mathrm{NO}}_2\to \text{odd electron species}$
${\mathrm{K}}_2\left[{\mathrm{NiCl}}_4\right]\to {\mathrm{Ni}}^{2+}\Rightarrow 3{\mathrm{d}}^8$ weak Ligand, C.N. = 4
$\Rightarrow$Tetrahedral, Paramagnetic with 2 unpaired electrons