Urea reacts with water to form $A$ which will decompose to form $B$. $B$ when passed through $Cu^{2+}_{(aq)}$,a deep blue coloured solution $C$ is formed. What is the formula of $C$ from the following?

$X$ is the number of electrons in $t_{2g}$ orbitals of the most stable complex ion among $[Fe(NH_3)_6]^{3+}$,$[Fe(Cl)_6]^{3-}$,$[Fe(C_2O_4)_3]^{3-}$ and $[Fe(H_2O)_6]^{3+}$. The nature of the oxide of vanadium of the type $V_2O_X$ is:

What is the color of the aqueous solution of $[Co(NH_3)_6]^{3+}$?

Match List-$I$ (Molar Conductivity) with List-$II$ (Complex Formula) and select the correct option:

List-$I$ (Conductivity)	List-$II$ (Formula)
$A. \ 229$	$i. \ [Pt(NH_3)_3Cl_3]Cl$
$B. \ 97$	$ii. \ [Pt(NH_3)_4Cl_2]Cl_2$
$C. \ 404$	$iii. \ [Pt(NH_3)_5Cl]Cl_3$
$D. \ 523$	$iv. \ [Pt(NH_3)_6]Cl_4$

$A$ solution contains $2.675 \ g$ of $CoCl_3 \cdot 6NH_3$ $(M = 267.5 \ g/mol)$. When passed through a cation exchanger,the chloride ions liberated are treated with excess $AgNO_3$ to yield $4.78 \ g$ of $AgCl$ $(M = 143.5 \ g/mol)$. What is the formula of the coordination compound?

The correct increasing order of trans-effect of the following species is: