The overall stability constant of the complex ion $[Cu(NH_3)_4]^{2+}$ is $2.1 \times 10^{13}$. The overall dissociation constant is $y \times 10^{-14}$. Then $y$ is ....... .(Nearest integer)

$A$ brown ring is formed in the ring test for $NO_{3}^{-}$ ion. It is due to the formation of :-

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

Violet colour of $[Ti(H_2O)_6]Cl_3$ on heating changes to $........$

$PtCl_4 \cdot 6H_2O$ can exist as a hydrated complex. Its $1 \ m$ aqueous solution has a depression in freezing point of $3.72 \ ^\circ C$. Assuming $100\%$ ionization and $K_f \ (H_2O) = 1.86 \ ^\circ C \ kg \ mol^{-1}$,the correct formula for the complex is:

Which of the following gives the maximum number of ions in aqueous solution?