When $CuSO_4$ solution in water is treated with concentrated $HCl$,it turns:

Assertion : $NF_3$ is a weaker ligand than $N(CH_3)_3$.
Reason : $NF_3$ ionizes to give $F^{-}$ ions in aqueous solution.

$Ag^{+} + NH_3 \rightleftharpoons [Ag(NH_3)]^{+}$; $k_1 = 3.5 \times 10^{-3}$
$[Ag(NH_3)]^{+} + NH_3 \rightleftharpoons [Ag(NH_3)_2]^{+}$; $k_2 = 1.7 \times 10^{-3}$
Then the formation constant of $[Ag(NH_3)_2]^{+}$ is

Copper sulphate solution reacts with $KCN$ to give

Which of the following complexes has the highest stability at $298 \ K$?

Which among the following does not form a white precipitate with $AgNO_3$ solution?