Correct Answer - Option 3 : (SiO
4)
4-
Concept:
The basic structural unit of feldspar, zeolites, mica and asbestos is SiO44-.
These are the examples of silicates, the basic unit of each of them is SiO.
Zeolites: Hydrated alumino silicates having negative charge which is balanced by cations such as Na+, K+ or Ca2+
Silicates Compounds with basic unit SiO44-, each Si atom is linked to four oxygen atom tetrahedrally, joined by corners. It is also known as hydrated aluminium silicate.
Mica: It is a potassium aluminium silicate KAl3Si3O10(OH2). The mica group of sheet silicate (phyllosilicate) minerals includes several closely related materials having nearly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition. The nearly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet-like arrangement of its atoms.
Asbestos is a hydrous magnesium silicate with the chemical composition: Mg3 Si2 O5 (OH2).
Asbestos is a term used to refer to six naturally occurring silicate minerals. All are composed of long and thin fibrous crystals; each fiber being composed of many microscopic 'fibrils' that can be released into the atmosphere by abrasion and other processes.
Asbestos is a well-known health hazard, and also used as a building material is now banned in many countries. Inhalation of the fibres can lead to various lung conditions, including asbestosis and cancer.
Feldspar is a potassium silicate KAlSi
3 O
8 and various sub-types of feldspar are available in earth crust. Silicate is a general name given to a group of minerals which have silicon-oxygen bonds with general formula
\({({S_ + }{O_4}^{x - })_n}\). Therefore, option (c) is correct.