Q17 / 160 · TS EAMCET 2019 (06 May Shift 1) · Chemistry

How many nearest neighbours are there for Si and O atoms in quartz crystals?

  • Correct answer
    A
    $4(\mathrm{Si}) ; 2(\mathrm{O})$
  • B
    $4(\mathrm{Si}) ; 4(\mathrm{O})$
  • C
    $2(\mathrm{Si}) ; 2(\mathrm{O})$
  • D
    $3(\mathrm{Si}) ; 2(\mathrm{O})$

Solution

Quartz is $\mathrm{SiO}_2$ (silicon dioxide) in which $\mathrm{SiO}_2$ units are present as giant crystal. In $\mathrm{SiO}_2$ crystal each $\mathrm{Si}$-atom is surrounded by 4 (O-atoms), i.e. has four nearest neighbours and each $\mathrm{O}$-atom is surrounded by two Si-atoms having two nearest neighbours. Figure
Hence, option (a) is correct.

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

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