Q.Which of the following statements is not correct?

A silicate is any mineral built from [SiO₄]⁴⁻ tetrahedra linked together in a characteristic pattern -- silicates and silica together make up nearly 95% of the earth's crust and underpin the entire glass and ceramics industries. Silicates are classified by how many oxygens each tetrahedron shares with its neighbours:

Ortho (neso) silicates -- discrete, unshared [SiO₄]⁴⁻ units (e.g. phenacite Be₂SiO₄, olivine (Fe/Mg)₂SiO₄). Pyro (soro) silicates -- two tetrahedra sharing one corner oxygen, giving [Si₂O₇]⁶⁻ (e.g. thortveitite Sc₂Si₂O₇). Cyclic (ring) silicates -- three or more tetrahedra closed into a ring, each sharing two oxygens, giving (SiO₃)ₙ²ⁿ⁻ (e.g. beryl). Inosilicates, split into chain silicates (pyroxenes) -- an open linear chain, each unit sharing two oxygens, (SiO₃)ₙ²ⁿ⁻ (e.g. spodumene) -- and double chain silicates (amphiboles) -- two cross-linked chains built from units sharing either two or three oxygens, [Si₄O₁₁]ₙ⁶ⁿ⁻ (e.g. asbestos). Sheet (phyllo) silicates -- each tetrahedro …