The "spin only" magnetic moment of $Ni^{2+}$ in aqueous solution would be [At. no. of $Ni = 28$]

The $d-$electron configurations of $Cr^{2+}, Mn^{2+}, Fe^{2+}$ and $Co^{2+}$ are $d^4, d^5, d^6$ and $d^7$ respectively. Which one of the following will exhibit minimum paramagnetic behaviour?
(At. nos. $Cr = 24, Mn = 25, Fe = 26, Co = 27$)

The diamagnetic species is

$CoSO_{4}Cl \cdot 5NH_{3}$ exists in two isomeric forms '$A$' and '$B$'. Isomer '$A$' reacts with $AgNO_{3}$ to give white precipitate,but does not react with $BaCl_{2}$. Isomer '$B$' gives white precipitate with $BaCl_{2}$ but does not react with $AgNO_{3}$. Answer the following questions.
$(i)$ Identify '$A$' and '$B$' and write their structural formulas.
$(ii)$ Name the type of isomerism involved.
$(iii)$ Give the $IUPAC$ name of '$A$' and '$B$.'

Which of the following will have three stereoisomeric forms?
$(i) \ [Cr(NO_3)_3(NH_3)_3]$
$(ii) \ K_3[Co(C_2O_4)_3]$
$(iii) \ K_3[CoCl_2(C_2O_4)_2]$
$(iv) \ [CoBrCl(en)_2]$

The complex $[Ti(H_2O)_6]^{3+}$ is paramagnetic in nature because...