Which ion in excess $NaOH$ does not form a soluble complex?

Which of the following represents the correct increasing order of the spectrochemical series (field strength) for some common ligands?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$NiCl_2 + NH_3$ (Excess) $\longrightarrow [Ni(NH_3)_6]^{2+}$

Given the following reactions:
$Ag^{+} + NH_3 \rightleftharpoons [Ag(NH_3)]^+ ; K_1 = 1.6 \times 10^3$
$[Ag(NH_3)]^+ + NH_3 \rightleftharpoons [Ag(NH_3)_2]^+ ; K_2 = 6.8 \times 10^3$
What is the formation constant for $[Ag(NH_3)_2]^+$?

$A$ complex containing $K^{+}$,$Pt(IV)$ and $Cl^{-}$ is $100\%$ ionised giving $i = 3$. Thus,the possible complex is

$[Cu(CN)_4]^{2-}$ is more stable than $[Cu(NH_3)_4]^{2+}$ because :-