Which of the following coordination complexes is heteroleptic?

Potassium ferrocyanide is a

In the coordination complex $[E(en)_2(C_2O_4)]NO_2$,the coordination number and oxidation state of $E$ are respectively:

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

$A$ $2 \ L$ solution is prepared by mixing $0.02 \ mol$ of $[Co(NH_3)_5SO_4]Br$ and $0.02 \ mol$ of $[Co(NH_3)_5Br]SO_4$. If $1 \ L$ of this mixture $X$ is treated with $AgNO_3$ to give $Y$,and another $1 \ L$ of mixture $X$ is treated with $BaCl_2$ to give $Z$,find the moles of $Y$ and $Z$.

$2.33 \ g$ 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 : $Co = 59, Cl = 35.5, Ag = 108$]