Which of the following is the formula of tartar emetic?

Identify the total number of complexes from the following list that contain only monodentate ligands:
$(a)$ $[Ni(CN)_4]^{2-}$ (Tetracyanonickelate $(II)$ ion)
$(b)$ $K_3[AlF_6]$ (Potassium hexafluoroaluminate $(III)$)
$(c)$ $[Cu(NH_3)_4]^{2+}$ (Tetraamminecopper$(II)$ ion)
$(d)$ $K_3[Al(C_2O_4)_3]$ (Potassium trioxalatoaluminate $(III)$)

The compounds having coordinated water are

$I$. $CrCl_3 \cdot 6 H_2 O$

$II$. $BaCl_2 \cdot 2 H_2 O$

$III$. $CuSO_4 \cdot 5 H_2 O$

Generally,a group of atoms can function as a ligand if:

Identify a ligand having two donor atoms but uses a pair of electrons of either donor atom to form a coordinate bond.

Assertion : When $NO$ reacts with $FeSO_4$,a brown coloured complex is formed.
Reason : In the complex,the coordination number of $Fe$ is $6$.