The formula of sodium nitroprusside is

The coordination number and oxidation state of $Cr$ in $K_3[Cr(C_2O_4)_3]$ are,respectively:

How many molecules of $EDTA$ (Ethylenediaminetetraacetic acid) are required to form an octahedral complex with a $Ca^{2+}$ ion?

Assertion : Ethylenediaminetetraacetate ion forms an octahedral complex with the metal ion.
Reason : It has six donor atoms which coordinate simultaneously to the metal ion.

$[EDTA]^{4-}$ is a .......

Given below are two statements :
Statement $I$ : $[Co(NH_3)_6]^{3+}$ is a homoleptic complex whereas $[Co(NH_3)_4 Cl_2]^{+}$ is a heteroleptic complex.
Statement $II$ : Complex $[Co(NH_3)_6]^{3+}$ has only one kind of ligands but $[Co(NH_3)_4 Cl_2]^{+}$ has more than one kind of ligands.
In the light of the above statements,choose the correct answer from the options given below.