Schottky defect is from Chemistry The Solid State

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 Multiple Choice QuestionsMultiple Choice Questions

201.

In a solid, a tom M occupies ccp lattice and 1/3rd of tetrahedral voids are occupied by atom N. Find the formula of solid formed by M and N.

  • M3N2

  • M2N3

  • M4N3

  • M3N4


202.

Assertion : The presence of a large number of Schottky defects in NaCl lowers its density.

Reason : In NaCl, there are approximately 106 Schottky pairs per cm3 at room temperature. 

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


203.

In tetragonal crystal system, which of following is not true?

  • All axial lengths and all axial angles are equal.

  • All three axial lengths are equal.

  • All three axial angles are equal.

  • Two axial angles are equal but the third is different.


204.

In solid ice, oxygen atom is surrounded

  • tetrahedrally by 4 hydrogen atoms

  • octahedrally by 2 oxygen and 4 hydrogen atoms

  • tetrahedrally by 2 hydrogen and 2 oxygen atoms

  • octahedrally by 6 hydrogen atoms


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205.

Schottky defect is

  • vacancy of ions

  • delocalization of ions

  • interstitial vacancy of ions

  • vacancy of only cations


A.

vacancy of ions

In Schottky defect, some of the lattice points are unoccupied, i.e. it consists of vacancies or holes. The number of missing cations and anions is the same, thus crystal remains neutral.


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206.

Assertion : bcc and hcp has same packing efficiency.

Reason : Both have same number of atoms per unit cell and same arrangement.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


207.

Assertion: Due to Frenkel defect, density of the crystalline solid decreases.

Reason : In Frenkel defect, cation or anion leaves the crystal.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


208.

Schottky defect in crystals is observed when

  • unequal number cations and anions are missing from the lattice

  • equal number of cations and anions are missing from the lattice

  • an ion leaves its normal site and occupies an interstitial site

  • density of the crystal is increased.


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209.

The coordination number in hcp is

  • 6

  • 12

  • 18

  • 24


210.

In face centred cubic unit cell edge length is :

  • 43r

  • 42r

  • 2r

  • 32r


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