Exercise

The coinage metals are 

Account for the following: $\mathrm{Zn}, \mathrm{Cd}, \mathrm{Hg}$ are considered as d-block elements but not as transition elements.
 

Account for the following: Chromates change their colour when kept in an acidic solution.

Account for the following: Copper (I) compounds are white whereas copper (II) compounds are coloured.

Give reason and select one atom/ion which will exhibit asked property : 
$\mathrm{Cr}$ or $\mathrm{Cu}$ (High melting and boiling point)

Calculate the spin only moment of ${\mathrm{Co}}^{2+} \left(\mathrm{Z}=27\right)$ by writing electronic configuration of $\mathrm{Co}$ and ${\mathrm{Co}}^{2+}$

Give reasons: ${\mathrm{Sc}}^{3+}$ is a colourless in aqueous solution whereas ${\mathrm{Ti}}^{3+}$ is coloured.

What is the change in oxidation number of sulphur during the oxidation of sulphite ion to sulphate ion by potassium permanganate in acidic medium?