Which of the following compounds is not colored yellow?

The sum of the total number of $Cr-O$ bonds in chromate $(CrO_4^{2-})$ and dichromate $(Cr_2O_7^{2-})$ ions is:

Match List-$I$ with List-$II$ and select the correct code:

List-$I$	List-$II$
$A$. Ziegler-Natta	$i$. $Fe_4[Fe(CN)_6]_3$
$B$. Brown ring complex	$ii$. $[Fe(H_2O)_5NO]SO_4$
$C$. Prussian Blue	$iii$. $Al(C_2H_5)_3 + TiCl_4$
$D$. Turnbull Blue	$iv$. $Fe_3[Fe(CN)_6]_2$

Correct code is:

Choose the correct statement$(s)$ among the following:
$(A)$ $[FeCl_4]^-$ has tetrahedral geometry.
$(B)$ $[Co(en)(NH_3)_2Cl_2]^+$ has $2$ geometrical isomers.
$(C)$ $[FeCl_4]^-$ has higher spin-only magnetic moment than $[Co(en)(NH_3)_2Cl_2]^+$.
$(D)$ The cobalt ion in $[Co(en)(NH_3)_2Cl_2]^+$ has $sp^3d^2$ hybridization.

The ammonia prepared by treating ammonium sulphate with calcium hydroxide is completely used by $NiCl_2 \cdot 6H_2O$ to form a stable coordination compound. Assume that both the reactions are $100 \%$ complete. If $1584 \ g$ of ammonium sulphate and $952 \ g$ of $NiCl_2 \cdot 6H_2O$ are used in the preparation,the combined weight (in grams) of gypsum and the nickel-ammonia coordination compound thus produced is $\qquad$ (Atomic weights in $g \ mol^{-1}: H=1, N=14, O=16, S=32, Cl=35.5, Ca=40, Ni=59$)

The number of ions present in $2 \ L$ of a solution of $1.6 \ M \ K_4[Fe(CN)_6]$ is: