Q65 / 200 · NEET 2007 · Chemistry

Which of the following anions is present in the chain structure of silicates?

  • A
    $\left(\mathrm{Si}_2 \mathrm{O}_5^{2-}\right)_n$
  • Correct answer
    B
    $\left(\mathrm{SiO}_3^{2-}\right)_n$
  • C
    $\mathrm{SiO}_4^{4-}$
  • D
    $\mathrm{Si}_2 \mathrm{O}_7^{6-}$

Solution

In silicates, two oxygen atoms per $\mathrm{SiO}_4$ tetrahedron are shared giving polymeric anion chains. When each tetetrahedron \(\left(\mathrm{SiO}_4^{4-}\right)\) shares two O atoms, infinite chains are formed. The formula of these extended anions approximates to \(\left(\mathrm{SiO}_3\right)_n^{2 n-}\) or \(\left(\mathrm{SiO}_3^{2-}\right)_n . \mathrm{SiO}_4^{4-}\) anion is present in orthosilicates. \(\mathrm{Si}_2 \mathrm{O}_7^{6-}\) anion is present in pyrosilicates, while \(\left(\mathrm{Si}_2 \mathrm{O}_5^{2-}\right)_n\) anion is present in double-chain silicates as well as in sheet silicates. Structure of silicate: Figure

Hence, the correct answer is option: 'B'.

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