The $\mathrm{d}-$ electron configuration of ${\mathrm{Cr}}^{2+},{\mathrm{Mn}}^{2+},{\mathrm{Fe}}^{2+}$ and ${\mathrm{Co}}^{2+}$ are ${\mathrm{d}}^4,{\mathrm{d}}^5,{\mathrm{d}}^6$and ${\mathrm{d}}^7$ respectively. Which one of the following will exhibit minimum paramagnetic behaviour?

Low spin complex of ${\mathrm{d}}^6$ -cation in an octahedral field will have the following energy: 

(${\mathrm{\Delta }}_{\mathrm{o}}=$ Crystal Field Splitting Energy in an octahedral field, $\mathrm{P}=$ Electron pairing energy)

Cobalt (III) chloride forms several octahedral complexes with ammonia. Which of the following will NOT give the test for chloride ions with silver nitrate at $25°\mathrm{C}$?