Question

Which one is the incorrect statement regarding 3D sheet silicates ?

• A. Negative charge on silicate is neutralised by positive charged metal ions.
• B. 3 corners of the silicates were shared to form 3D network
• C. Quartz and Tridymite are 3D sheet silicates
• D. Silicate units are links together to form 3D silicates

Answer 1

The correct option is B 3 corners of the silicates were shared to form 3D network

The general formula of three dimensional (3 - D) or tecto or Framework silicates is $(Si{O}_2{)}_n.$ All the oxygen atoms of $Si{O}_4$(4 oxygen) are shared with other tetrahedra and thus by forming three-dimensional network.

E.g. $Si{O}_2$ - Quartz, Tridymite and Crystobalite - These are the crystalline forms of silica.

When $Si{O}_4^{4-}$ units are replaced by $Al{O}_4^{5-}$ units, three dimensional aluminosilicates are formed.
E.g. Feldspar, Zeolites, etc.,

Negative charge on silicate structure is neutralised by positively charged metal ions.