In hemoglobin, the metal ion present is:

The reagent used for the detection of $Ni^{2+}$ is $A$. $x$ moles of $A$ react with $Ni^{2+}$ to form a complex of $C$ color. $A$,$x$,and $C$ are respectively:

For silver plating of copper,$K[Ag(CN)_2]$ is used instead of $AgNO_3$. This is because ........

Sodium thiosulphate $(Na_2S_2O_3 \cdot 5H_2O)$ is used in photography to

For lead poisoning,the antidote used is:

The wrong match is: