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Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following statement(s) is/are incorrect regarding the defects in solids?

  1. $AgBr$ crystal show both Schottky and Frenkel defect

  2. Impurity defect by doping of Arsenic in Silicon results n-type semiconductor

  3. Doping in crystal introduces dislocation defect

  4. Metal deficient defect can occur with extra anion present in the interstitial voids
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Multiple choice imperfections in solids solid state the solid state chemistry

The correct statement(s) regarding defects in solid is (are)

  1. Frenkel defect usually favoured by a very small difference in the sizes of cation and anion

  2. Frenkel defect is a dislocation defect

  3. Trapping of an electron in the lattice leads to the formation of F-centre

  4. Schottky defect have no effect on the physical properties of solids
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Multiple choice imperfections in solids solid state the solid state chemistry

Missing of one cation and one anion from the crystal lattice is called

  1. ionic defect

  2. crystal defect

  3. schottky defect

  4. frenkel defect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Schottky defect arises due to a vacancies at cation sites and equal number of vacancies at anion sites.

Hence, option C is correct.

Multiple choice imperfections in solids solid state the solid state chemistry

In a crystal, pair of ions are missing from normal sites. This is an example of which defect?

  1. Extended defect

  2. Interstitial defect

  3. Frenkel defect

  4. Schottky defect
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Schottky defect arises due to a vacancies at cation sites and equal number of vacancies at anion sites.

Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following crystals does not exhibit Frenkel defect?       

  1. $AgBr$
  2. $AgCl$
  3. $KBr$
  4. $ZnS$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Condition for Frankel defects in an ionic crystal is-

  1. The size difference between the ions should be large.
  2. Smaller ion (cation) move to interstitial site.

Frenkel defect generally appears in ZnS, AgBr, AgI, AgCl etc.
Alkali metal shows Schottky defect. Here KBr exhibits Schottky defect. However, it does not show Frankel defect. ZnS has a large size difference between the ions.

Option C is correct.

Multiple choice imperfections in solids solid state the solid state chemistry

The correct statement(s) regarding defects in solids is(are):

  1. Frenkel defect is usually favoured by a very small difference in the sizes of cation and anion.

  2. Frenkel defect is a dislocation defect.

  3. Trapping of an electron in the lattice leads to the formation of F-center

  4. Schottky defects have no effect on the physical properties of solids.
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

Frenkel defect is a defect which is created when an ion leaves its appropriate site in the lattice and occupies an interstitial site. A hole or vacancy is thus produced in the lattice.
Frenkel defect is exhibited in ionic compounds in which the radius ratio is low. The cations and anions differ much in their sizes and the ions have low co-ordination numbers. Examples are ZnS, AgBr, AgI, AgCl.
The Schottky defect is a defect which is produced when one cation and anion are missing from their respective positions leaving behind a pair of holes. The crystal as a whole remains neutral because the number of missing positive ions (cations) and negative ions (anions) is the same.

Consequences of Schottky defect:
1. The density of the crystal decreases.
2. The crystal begins to conduct electricity to a small extent by the ionic mechanism.
3. The presence of too many voids lowers lattice energy or the stability of the crystal.
4. F-center: A colour centre consisting of an electron trapped by a negative ion vacancy in an ionic crystal such as an alkali halide or an alkaline-earth fluoride or oxide.

Hence, the correct options are $\text{B}$ and $\text{C}$.

Multiple choice imperfections in solids solid state the solid state chemistry

Scotty defect is observed in____________.

  1. $NaCl$
  2. $KCl$
  3. $CsCl$
  4. $BaCl _2$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Schottky defect is the defect which is produced when one cation and anion are missing from their respective positions leaving behind a pair of holes. The crystal as a whole remains neutral because the number of missing positive ions (cations) and negative ions (anions) is the same.
For Schottky defect, co-ordination numbers of the ions should be high., Examples of ionic solids showing this defect are NaCl, CsCl, KCI, KBr etc.
Consequences of Schottky defect are as follows:
1. Density of the crystal decreases.
2. The crystal begins to conduct electricity to small extent by ionic mechanism.
3. The presence of too many voids lowers lattice energy or the stability of the crystal.

Multiple choice imperfections in solids solid state the solid state chemistry
Statement: The imperfectness in crystal increases with increase in temperature.

State whether the given statement is true or false

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The imperfectness in crystal increases with increase in temperature. Hence, these imperfections are called thermodynamic defects. When the temperature is high, imperfections are high and when the temperature is low, imperfections are low.
Multiple choice imperfections in solids solid state the solid state chemistry
Statement: Imperfection in solids give rise to new properties in it.

State whether the given statement is true or false

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Imperfection in solids changes the properties of crystals and gives rise to new properties in it. These include electrical and thermal conductivity and density.