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

The number of moles of $NH_{3}$ that must be added to $2 \, L$ of $0.80 \, M \, AgNO_{3}$ in order to reduce the concentration of $Ag^{+}$ ions to $5.0 \times 10^{-8} \, M$ ($K_{\text{formation}}$ for $[Ag(NH_{3})_{2}]^{+} = 1.0 \times 10^{8}$) is ...... . (Nearest integer)
[Assume no volume change on adding $NH_{3}$ ]

Aluminium trifluoride is insoluble in anhydrous $HF$ but dissolves on addition of $NaF$. Aluminium trifluoride precipitates out of the resulting solution when gaseous $BF_3$ is bubbled through. Give reasons.

Nitrate is confirmed by the ring test. The brown color of the ring is due to the formation of:

Which equilibrium can be described as an acid-base reaction using the Lewis acid-base definition but not using the Bronsted-Lowry definition?

What is meant by the chelate effect? Give an example.