What is the calculated value of spin-only magnetic moment in terms of $BM$ if only one unpaired electron is present in a species?

Which of the following statements is correct?

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

$[Ti(H_2O)_6]^{3+}$ is paramagnetic in nature due to

$A$ complex $[CoL_6]^{n+}$ where $L$ is a neutral ligand has a magnetic moment $\mu = 4.5 \ BM$. Hence,

Select the correct pair of complexes that exhibit the same type of isomerism: