Dimethyl glyoxime gives a red precipitate with $Ni^{2+}$,which is used for its detection. To get this precipitate readily,the best $pH$ range is

Sodium nitroprusside when added to an alkaline solution of sulphide ions produces a:

Aqueous solution of a metallic nitrate $X$ reacts with $NH_4OH$ to form $Y$,which dissolves in excess $NH_4OH$. The resulting complex is reduced by acetaldehyde to deposit the metal. $X$ and $Y$,respectively,are

Turnbull's blue is a compound

The compound used in the treatment of lead poisoning is

Hypo is used in photography because of its