Tag: imperfections in solids

Questions Related to imperfections in solids

Which of the following defects decrease the density?

imperfections in solids solid state the solid state chemistry

  1. Interstitial defect

  2. Vacancy defect

  3. Frenkel defect

  4. Schottky defect

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Correct Option: B,D
Explanation:

Vacancy and Schottky defect which lead to decrease the density both are the types of a stoichiometric defect. In case of Frenkel defect and interstitial defect, there is no change in density of substance.

Frenkel defect is also known as

imperfections in solids solid state the solid state chemistry

  1. stoichiometric defect

  2. dislocation defect

  3. impurity defect

  4. non-stoichiometric defect

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Correct Option: A,B
Explanation:

(a, b) In Frenkel defect, dislocation of cations takes place and there is no change in stoichiometry of the crystal.

Iron (II) oxide is written as $\overline{FeO}$. What does it mean?

imperfections in solids solid state the solid state chemistry

  1. Fully pure

  2. Impure

  3. Ratio of $Fe$ and $O $ is 1:1

  4. None of these

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Correct Option: B
Explanation:

Impurity defects are foreign atoms that replace some  of the atoms making up the solid or that squeeze into the interstices; they are important in the electrical behaviour of semiconductors, which are materials used in computer chips and other electronic devices.

An example of interstitial impurity  atoms is the carbon atoms that are added to iron to make steel.

Formula of metal oxide with metal deficiency defect in its crystal is $A _{0.8}O$. The crystal contains $A^{2+}$ and $A^{3+}$ ions. The fraction of metal existing as $A^{2+}$ ions in the crystal is

imperfections in solids solid state the solid state chemistry

  1. $0.96$

  2. $0.04$

  3. $0.50$

  4. $0.31$

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Correct Option: C
Explanation:

Solution:- (C) $0.50$

Fiormula is ${A} _{0.8}O$
So the ratio of $A : O = 80 : 100$
Thus, if there are $100$ atoms of oxygen then $80$ atoms of $A$.
Let $x$ be the no. of atopms of ${A}^{+2}$.
No. of atoms of ${A}^{+3} = 80 - x$
Charge on $A \; =$ Charge on $O$
Since oxygen has charge $-2$.
Therefore,
$2x + 3 \left( 80 - x \right) = 2 \times 100$
$2x + 240 - 3x = 200$
$\Rightarrow x = 40$
Therefore,
Fraction of ${A}^{+2} = \cfrac{\text{atoms of } {A}^{+2}}{\text{Total no. of atoms}}$
$\Rightarrow$ Fraction of ${A}^{+2} = \cfrac{40}{80} = 0.50$

The non-stoichiometric compound, titanium monoxide has a continuous range of composition from $Ti _{0.75}O$ to $TiO _{0.69}$ Which of the following is/are the correct regarding the possible composition of the compound ? $[Ti=48]$

imperfections in solids solid state the solid state chemistry

  1. The maximum percentage by mass of oxygen in the compound is $30.8$

  2. The minimum percentage by mass of titanium in the compound is $69.2$

  3. The minimum percentage by mass of oxygen in the compound is $18.7$

  4. The minimum percentage by mass of titanium in the compound is $82.3$

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Correct Option: A,B,C

Frenkel defect is noticed in 

imperfections in solids solid state the solid state chemistry

  1. $AgBr$

  2. $ZnS$

  3. $AgI$

  4. All

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Correct Option: D

Which of the following defect, if present, lowers the density of the crystal?

imperfections in solids solid state the solid state chemistry

  1. Frenkel

  2. Schottky

  3. Metal excess defect due to excess cation

  4. interstitial defect

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Correct Option: B

The schottky defect appears in

imperfections in solids solid state the solid state chemistry

  1. $NaCl$

  2. $CsCl$

  3. $AgBr$

  4. All

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Correct Option: D

The only incorrect effect on density by the given defect in solids is

imperfections in solids solid state the solid state chemistry

  1. Density must decrease by vacancy defect

  2. Density must increase by the interstitial defect

  3. Density must increase by impurity defect

  4. Density does not change by dislocation defect

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Correct Option: C

The intrinsic or thermodynamic defect is

imperfections in solids solid state the solid state chemistry

  1. Schottky defect

  2. Metal excess defect due to excess cation

  3. Metal excess defect due to anion vacancy

  4. Metal-deficient defect

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Correct Option: A