STD 12 - 4. d and f- block elements — JEE STD 11 Science — Question

trans $\left( Ph - CH = CH - CH _3\right) \rightarrow$ cis $\left( Ph - CH = CH - CH _3\right)$

$(a)$ Octahedral $Co(III)$ complexes with strong field ligands have very high magnetic moments

$(b)$ When $\Delta_{0}< P$, the $d-$electron configuration of $Co(III)$ in an octahedral complex is $t_{\text {eg }}^{4} e_{g}^{2}$

$(c)$ Wavelength of light absorbed by $\left[\mathrm{Co}(\mathrm{en})_{3}\right]^{3+}$ is lower than that of $\left[\mathrm{CoF}_{6}\right]^{3-}$

$(d)$ If the $\Delta_{0}$ for an octahedral complex of $\mathrm{Co}(\mathrm{III})$ is $18,000 \;\mathrm{cm}^{-1},$ the $\Delta_{\mathrm{t}}$ for its tetrahedral complex with the same ligand will be $16,000\;\mathrm{cm}^{-1}$