The name of the ring structure complex compound formed between a metal ion and a polydentate ligand is . . . . . . .

In dichlorodioxalatochromium$(III)$,the primary and secondary valencies are respectively ......

Explain the following term with an example: Bidentate ligands.

$2.33 \ g$ of compound $X$ (empirical formula $= CoH_{12}N_{4}Cl_{3}$) upon treatment with excess $AgNO_{3}$ solution produces $1.435 \ g$ of a white precipitate. The primary and secondary valences of cobalt in compound $X$,respectively are.
[Given,atomic mass : $Co = 59, Cl = 35.5, Ag = 108$]

Which of the following is a bidentate negatively charged ligand?

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.