JEE Main 2024 — 5 April, Shift 2 — Question 75

$[\mathrm{TiCl_4}]$: Titanium is in the $+4$ oxidation state ($d^0$); therefore, in a tetrahedral field, the $t_2$ orbitals remain vacant. $[\mathrm{MnO_4}]^{-}$: Manganese is in the $+7$ oxidation state ($d^0$); hence, there are no electrons in the $t_2$ orbitals. $[\mathrm{FeO_4}]^{2-}$: Iron is in the $+6$ oxidation state ($d^2$); in a tetrahedral field, electrons occupy the lower-energy $e$ orbitals first, leaving the $t_2$ orbitals empty. $[\mathrm{FeCl_4}]^{-}$: Iron is in the $+3$ oxidation state ($d^5$); therefore, electrons occupy the $t_2$ orbitals. $[\mathrm{CoCl_4}]^{2-}$: Cobalt is in the $+2$ oxidation state ($d^7$); hence, the $t_2$ orbitals are occupied. Thus, the number of complexes having no electrons in the $t_2$ orbitals is $3$.