Which of the following compounds has a zero magnetic moment?

Which one of the following compounds is not coloured?

Which of the following will have a spin-only magnetic moment of $2.86 \ BM$?

Identify the complex ion with spin only magnetic moment of $4.90 \ BM$.

Consider the following statements and select the correct option using the codes given.
$(i)$ $[Cr(NH_3)_6][Cr(CN)_6]$ and $[Cr(NH_3)_4(CN)_2][Cr(NH_3)_2(CN)_4]$ are coordination isomers.
$(ii)$ $[Cr(py)_2(H_2O)_2Cl_2]Cl$ and $[Cr(py)_2(H_2O)Cl_3]H_2O$ are linkage isomers.
$(iii)$ $[Pt(NH_3)_4Br_2]Cl_2$ and $[Pt(NH_3)_4Cl_2]Br_2$ are linkage isomers.
$(iv)$ $[NiCl_2(PPh_3)_2]$ (tetrahedral) exhibits geometrical isomerism.

Identify the correct pair of properties of the $[Co(NH_3)_6]^{3+}$ complex ion.