Tag: solid state

Quizzes (4) Questions (214)

Questions Related to solid state

Multiple choice imperfections in solids solid state the solid state chemistry

Give the correct order of initials T(true) or F(False) for following statements:
I. In an anti-fluorite structure, anions form FCC and cations occupy all the tetrahedral voids
II. If the radius of cation and anion is $20$ and $95$ pm, then the coordination number of the cation is the crystal is $4$.
III. An atom or ion is transferred from a lattice site to an interstitial position in Frenkel defect.
IV. The density of crystal always increases due to substitutional impurity defect.

  1. TTTT

  2. FFFF

  3. FFTT

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

I is False: In anti-fluorite, anions form FCC and cations occupy all tetrahedral voids. II is True: Radius ratio 20/95 = 0.21, which falls in the range for coordination number 4. III is True: This is the definition of Frenkel defect. IV is False: Density can decrease if the impurity atom is smaller or lighter.

Multiple choice imperfections in solids solid state the solid state chemistry

Which kind of defect is introduced by doping in silicon crystal?

  1. Dislocation defect

  2. Schottky defect

  3. Frenkel defect

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

Doping silicon with elements like phosphorus or boron introduces extra electrons or holes, which are classified as electronic defects, altering the electrical conductivity of the semiconductor.

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 $\text{C}$.