(a) Account for the following :
(i) `Mn_(2)O_(7)` is acidic whereas MnO is basic.
(ii) Though copper has completely filled d-orbital `(d^(10))` yet it is considered as a transition metal.
(iii) Actinoids show wide range of oxidation states.
(b) Write the preparation of potassium permanganate from pyrolusite ore `(MnO_(2))`.

Explanation

(a) (i) `Mn_(2)O_(7)` (+7 oxidation state ) is acidic whereas MnO(+2 oxidation state ) is of basic nature.
For example
`underset("(Acidi)")((Mn_(2)O_(7))+2KOH to 2KMnO_(4)+H_(2)O`
`underset("(Basic)")(MnO)+2HCl to MnCl_(2)+H_(2)O`
(ii) Copper has `[Ar]4s^(1)3d^(10)` electronic configuration. However, in its most common oxidation state (+2), 3d orbitals are not completely filled (i.e., `3d^(9)` configuration). THerefore, it is regarded as a transition metal.
(iii) N/A
(b) N/A