Tag: the solid state

Quizzes (4) Questions (85)

Questions Related to the solid state

Multiple choice imperfections in solids solid state the solid state chemistry

$KBr$ shows, which of the following defects?

  1. Frenkel defect

  2. Schottky defect

  3. Metal excess defect

  4. Metal deficiency
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Schottky defect is shown in highly ionic compound, highly coordinated compounds, and where there is only a small difference in sizes of cations and anions of which the compound lattice is composed.

Examples:- $NaCl, KCl, KBr, CsCl, AgBr$

Multiple choice imperfections in solids solid state the solid state chemistry

In a non-stochiometric sample of cuprons sulphide, with the composition $Cu _{1.8}$, cupric ions are also present in the lattice. The mole % of $Cu^{2+}$ present in the copper content of the crystal is:

  1. $99.9$%
  2. $11.11$%
  3. $88.88$%
  4. $18$%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$180 \ Cu$ atoms are associated with $100 \ S$ atoms.

Let $x$ atoms be present as $Cu^{+}$
Total charge on $xCu^+$ and $(180-x)Cu^{2+}$ must be equal to total charge on $100 \ S^{2-}$ ions.
So, $x+2(180-x)=2 \times 100$
$x+360-2x=200$
$x=160$
% of $Cu^{+}$ ions $= \cfrac {160}{180} \times 100=88.9$%

Multiple choice imperfections in solids solid state the solid state chemistry

If $NaCl$ is doped with ${ 10 }^{ -4 }mol$% of ${ SrCl } _{ 2 }$, the concentration of cation vacancies will be: $\left( { N } _{ A }=6.02\times { 10 }^{ 23 }{ mol }^{ -1 } \right) $:

  1. $6.02\times { 10 }^{ 15 }{ mol }^{ -1 }$
  2. $6.02\times { 10 }^{ 16 }{ mol }^{ -1 }$
  3. $6.02\times { 10 }^{ 17 }{ mol }^{ -1 }$
  4. $6.02\times { 10 }^{ 14 }{ mol }^{ -1 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$NaCl$ is doped with $10^{-4}$ $mol\%$ of $SrCl _2$, i.e., one mole of $NaCl$ will have $10^{-6}$ mol of $SrCl _2$

$\rightarrow Sr^{+2}$ will replace one cation.
Therefore, concentration of cation vacancy $=10^{-6}\times 6.022\times 10^{23}=6.022\times 10^{17}$ $mol^{-1}$

Multiple choice imperfections in solids solid state the solid state chemistry

The mineral hawleyite, one form of $CdS$, crystallizes in one of the cubic lattices , with edge length 5.87 A The density of hawleyite is $ 4.63 g cm^{-3} $
In which cubic lattice does hawleyite crystallizes?

  1. end centred cubic

  2. body centered cubic

  3. face centred cubic

  4. edge centred cubic
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Density of Howlegite $=4.63g/{ cm }^{ 3 }$  $(P)$

Edge length $={ 5.87A }^{ 0 }=5.87\times { 10 }^{ -8 }cm$ $(a)$
Density $\left( P \right) =\dfrac { z\times { a }^{ 3 }\times { N } _{ 0 } }{ M } $                                 $M=$ Molar mass of $cds=144g/mol$
$z=\dfrac { 4.63\times { \left( 5.87\times { 10 }^{ -8 } \right)  }^{ 3 }\times 6.02\times { 10 }^{ 23 } }{ 144 } $        $N=$ Avagadro Number $=6.023\times { 10 }^{ 23 }$
$=3.9\cong 4\quad \quad z=4$
$\therefore$   There are four formula units of cds present in on unit cell.
$\Rightarrow $  Face entered cubic lattice.

Multiple choice imperfections in solids solid state the solid state chemistry

Which is correct statement?

  1. Schottky defect occurs when radius of cation is smaller

  2. When temperature increases then number of defects decreases

  3. Frenkel defect occurs when radius of cation is smaller

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

As temperature and number of defects are inversely propotional, with increase in temperature number of defects decreases. 

In schottky effect, size of ions are almost same while in frenkel defect, size of cation is small .

Multiple choice imperfections in solids solid state the solid state chemistry

(i) Frenkel defect create a vacancy defect at its original site and an interstitial defect at its new position.
(ii) Frenkel defect is stoichiometric point defect.
(iii) Frenkel defect is also called dislocation defect.
(iv) Silver halide shows Frenkel defect 
Select the correct statements :

  1. $(ii),(iii),(iv)$ only
  2. $(i),(ii),(iii)$ only
  3. $(i),(ii),(iii),(iv)$
  4. $(i),(ii),(iv)$ only
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

All statements are correct: Frenkel involves vacancy and interstitial sites, is stoichiometric, is called a dislocation defect, and is common in silver halides.

Multiple choice imperfections in solids solid state the solid state chemistry

$NaCl$ shows Schottky defects and $AgCl$ Frenkel defects. Their electrical conductivity is due to ________.

  1. motion of ions and not the motion of electrons

  2. notion of electrons and not the motion of ions
  3. lower coordination number of $NaCl$
  4. higher coordination number of $AgCl$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In ionic solids like NaCl and AgCl, electrical conductivity is primarily due to the migration of ions through vacancies or interstitial sites, not the movement of electrons.

Multiple choice imperfections in solids solid state the solid state chemistry

Metallic or non-stoichiometric (or interstitial) hydrides are formed by:

  1. Many d-block and f-block elements.

  2. Many s-block elements

  3. Many p-block elements

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Metallic or interstitial hydrides are typically formed by d-block and f-block transition metals where hydrogen occupies interstitial sites in the metal lattice.

Multiple choice imperfections in solids solid state the solid state chemistry

Calculate the dencity of NaCl type ionic solid AB($M _{w}$=60) in $gm/CM^{3}$ if shortest distance between two nearest neighbours is 100 pm &solid having $20\%$ schottky defect$(N _{A}=6\times10^{23}$)

  1. 10

  2. 20

  3. 30

  4. 40
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice imperfections in solids solid state the solid state chemistry

When NaCl is doped with ${ 10 }^{ -3 }$ mole % of Sr${ Cl } _{ 2 }$, what is the number of cationic vacancies?

  1. ${ 10 }^{ -5 }\times { N } _{ A }$
  2. ${ 10 }^{ -7 }\times { N } _{ A }$
  3. 6.022$\times{ 10 }^{8 }{ N } _{ A }$

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer