Question

The example of cyclic silicate is:
A. \[{{B}}{{{e}}_3}{{A}}{{{l}}_2}\left[ {{{S}}{{{i}}_6}{{{O}}_{18}}} \right]\]
B. ${{A}}{{{l}}_2}{\left( {{{OH}}} \right)_4}{{S}}{{{i}}_2}{{{O}}_5}$
C. \[{{N}}{{{a}}_6}\left[ {{{A}}{{{l}}_6}{{S}}{{{i}}_6}{{{O}}_{24}}} \right]{{{S}}_2}\]
D. ${{Z}}{{{n}}_2}\left( {{{Si}}{{{O}}_4}} \right)$

Answer 1

Hint: Before finding out the examples of cyclic silicates, we have to find what silicates and cyclicates are. Silicates are the compounds which have silicon and oxygen as elements. Their basic unit is silica-oxygen tetrahedron.

Complete step by step answer:
The silicate structures are classified into several types. They are nesosilicates or orthosilicates, sorosilicates or pyrosilicates, cyclic silicates or ring silicates, chain silicates or pyroxenes, double chain silicates or amphiboles, sheet or phyllosilicates and three dimensional or tectosilicates.
They are linked in several different patterns. Depending on this pattern, silicates are classified.
Now let’s move to cyclic silicates.
The silicates have rings of linked ${{Si}}{{{O}}_4}$ tetrahedron which has a ratio of ${{Si:O = 1:3}}$ . Also, it contain ${\left( {{{Si}}{{{O}}_3}} \right)_{{n}}}^{2{{n}} - }$. These rings may have three, four, or six groups of tetrahedra. They are very strong minerals.
A common example of cyclic silicates or ring silicates is Beryl. Its chemical formula is, \[{{B}}{{{e}}_3}{{A}}{{{l}}_2}{\left[ {{{Si}}{{{O}}_3}} \right]_6}\]. It is known as an aluminosilicate. In this silicate, there are six silicate rings. Six oxygen atoms are surrounded to each aluminium octahedrally. Emerald and aquamarine are well known varieties of beryl.
Another example of cyclic silicates is Benitoite, ${{BaTi}}{\left( {{{Si}}{{{O}}_3}} \right)_3}$.
In other options, they are not in the ratio of ${{Si:O = 1:3}}$. Thus \[{{B}}{{{e}}_3}{{A}}{{{l}}_2}{\left[ {{{Si}}{{{O}}_3}} \right]_6}\] is the example of cyclic silicates.
Hence, the correct option is A.

Note: Two oxygen atoms are shared and arranged in a ring in a cyclic silicate. Three membered ring silicates or cyclic silicates have ${{S}}{{{i}}_3}{{{O}}_9}^{6 - }$ ions. Four membered sing silicates have ${{S}}{{{i}}_4}{{{O}}_{12}}^{8 - }$ ions and five membered ring silicates have ${{S}}{{{i}}_5}{{{O}}_{15}}^{10 - }$.