Which of the following is a weak field ligand?

$A$ transition metal $(M)$ among $Mn, Cr, Co$ and $Fe$ has the highest standard electrode potential $(M^{3+} / M^{2+})$. It forms a metal complex of the type $[M(CN)_6]^{4-}$. The number of electrons present in the $e_g$ orbital of the complex is $.........$

The crystal field theory is successful in explaining which of the following?
$I.$ Ligands as point charges;
$II.$ Formation and structures of complexes.
$III.$ Colour;
$IV.$ Magnetic properties;
$V.$ Covalent character of metal-ligand bonding.

The electronic spectrum of $[Ti(H_2O)_6]^{3+}$ gives a single broad peak with a maxima at $20300 \, cm^{-1}$. The crystal field stabilization energy is equal to .......... $kJ \, mol^{-1}$

In the spectrochemical series, the positions occupied by the ligands $Cl^{-}$, $OH^{-}$, and $CN^{-}$ in increasing order of their crystal field splitting power are:

In the complex ion $ML_6^{n+}$,$M^{n+}$ has five $d$-electrons and $L$ is a weak field ligand. According to crystal field theory,the magnetic property of the complex ion is due to how many unpaired electrons?