Question

In Nessler’s reagent, the active ion is:

• A. $A{g}^{+}$
• B. $H{g}^{2+}$
• C. $[Hg{I}_3{]}^{-}$
• D. $[Hg{I}_4{]}^{2-}$

Answer 1

The correct option is D $[Hg{I}_4{]}^{2-}$

Potassium tetraiodomercurate(II) $\left(K_2\right[Hg{I}_4\left]\right)$ is called Nessler's reagent. It is used for qualitative analysis of $N{H}_4^{+}$ ions.
The active ion in Nessler's reagent is $[Hg{I}_4{]}^{2-}$