Question

Quartz is an example of
(A) chain silicate
(B) Sheet silicate
(C) Cyclic silicate
(D) 3D network silicate

Answer 1

Quartz contains ${\text({SiO}}_4)^{4 - }$ tetrahedral units. Each ${\text({SiO}}_4)^{4 - }$ tetrahedral unit shares three corners.

Complete answer:
Most common minerals found in the earth are silicate minerals. Examples of silicate minerals are quartz, zeolites, mica, feldspar, pyroxene, amphibole, serpentine, talc, chlorite, clay and olivine. Silicate minerals contain ${\text({SiO}}_4)^{4 - }$ tetrahedral units. In this tetrahedral unit, the silicon atom is at the center and four oxygen atoms are at four corners of the regular tetrahedron. Individual ${\text({SiO}}_4)^{4 - }$ tetrahedral units are joined to form rings, chains, and 3-D structures..
The empirical formula of sheet silicates is $\left( {{\text{S}}{{\text{i}}_2}{{\text{O}}_5}} \right)_n^{2n - }$
Quartz is an example of Sheet silicate.
(A) In chain silicates, each tetrahedral unit shares two oxygen atoms. It forms a linear single stranded chain.
(B) In sheet silicates, each tetrahedral unit shares three corners. An infinite two dimensional sheet is formed.
(C) Cyclic silicate is, each tetrahedral unit shares two oxygen atoms. It forms a closed ring structure.
(D) In 3D network silicates, each tetrahedral unit shares four oxygen atoms. A three dimensional network structure is obtained.
Thus, silicates contain tetrahedral units. They are represented with small open circles and small closed circles. The open circles represent oxygen atoms. The closed circle represents silicon atoms.

Hence, the correct option is the option (B).

Note: Quartz is crystalline in nature and is very hard material. It contains ${\text({SiO}}_4)^{4 - }$ tetrahedral units in oxygen atoms that share two tetrahedral units. The chemical formula of quartz is ${\text{Si}}{{\text{O}}_2}$.