The hydrated $Cu^{2+}$ ion is:

When $Co(II)$ chloride is dissolved in concentrated $HCl$,a blue solution is obtained. Upon dilution with water,the colour changes to pink because:

Which of the following represents the correct increasing order of the spectrochemical series (field strength) for some common ligands?

$K_4[Fe(CN)_6]$ reacts with ozone to give:

Cobalt$(III)$ chloride forms a green coloured complex '$X$' with $NH_3$. The number of moles of $AgCl$ formed when an excess of $AgNO_3$ solution is added to $100 \ mL$ of a $1 \ M$ solution of '$X$' is:

The aqueous solution of a transition metal salt changes colour from pink to blue when concentrated hydrochloric acid is added to it. The change in colour is due to: