(i) Aluminium does not occur free in nature. It is most abundant metal in the earth's crust.

(ii) lmportant minerals are

(a) Bauxite : `Al_2O_3*2H_2O`

(b) Diaspore : `Al_2O_3 * H_2O`

(c) Corrundum : `Al_2O_3`

(d) Cryolite : `Na_3AlF_6`

(e) Feldspar : `KAlSi_3O_8 text(or) K_2O . Al_2O_3 . 6 SiO_2`

(iii) Among binary compounds of `Al` only `AlF_3` & `Al_2O_3` are ionic.

(iv) Extraction of `Al` is done from bauxite `(Al_2O_3*2H_2O)` by electrolysis. The process involves :

(a)Purification of bauxite

(b) Electrolytic reduction of alumina

(c) Purification of `Al`

(v) Bauxite is associated with impurities of `Fe_2O_3`, `SiO_2` & `TiO_2`. The method of purification depends upon the nature of impurity.