Impurity Defect

Q.

Which of the following statements are not true?

(a) Vacancy defect results in a decrease in the density of the substance

(b) Interstitial defects result in an increase in the density of the substance

(c) Impurity defect has no effect on the density of the substance

(d) Frenkel defect results in an increase in the density of the substance

Q.

How Do Impurities Affect Freezing Point ?

Q.

How do you calculate freezing point depression?

Q. Which solid is formed when a viscous liquid is cooled rapidly?

1. Eutectic solid
2. Crystalline solid
3. Amorphous solid
4. None of the above

Q.

Impurity defect is the defect in which

1. Both cations and anions miss from their lattice sites creating voids.

2. Ions are replaced by different elements ions.

3. Anions occupy interstitial voids.

4. electrons occupy interstitial voids.

Q.

Zinc sulphide is crystalline solid:

1. Because of large number of particles.

2. Because of scattering particles.

3. Because of periodicity in definite arrangement of particles.

4. Because of non periodicity in arrangement of particles.

Q.

The following is not a function of an impurity present in a crystal

[MP PET 1995]

1. Establishing thermal equilibrium

2. Having tendency to diffuse

3. Contributing to scattering

4. Introducing new electronic energy levels

Q.

Which of the following diagrams is of impurity defect?

1. 

2. 

3. 

4. 

Q.

Impurity defect is the defect in which

1. Both cations and anions miss from their lattice sites creating voids.

2. Ions are replaced by different elements ions.

3. Anions occupy interstitial voids.

4. electrons occupy interstitial voids.

Q. When $NaCl$ is doped with ${10}^{-5}$ moles % of $SrC{l}_2$, what is the number of cationic vacancies per mole?

1. ${10}^{-5}\times N_A$
2. ${10}^{-7}\times N_A$
3. None of these
4. $2\times {10}^{-7}{N}_A$

Q. If NaCl is doped with ${10}^{-3}mol$% $SrC{l}_2$, then the concentration of cation vacancies will be

1. $1\times {10}^{-3}mol$%
2. $2\times {10}^{-3}mol$%
3. $3\times {10}^{-3}mol$%
4. $4\times {10}^{-3}mol$%

Q. If $NaCl$ is doped with ${10}^{-3}$ mol % of $SrC{l}_2$, the concentration of cation vacancies per mol of $NaCl$ is

1. $6.02\times {10}^{20}$
2. $6.02\times {10}^{22}$
3. $6.02\times {10}^{23}$
4. $6.02\times {10}^{18}$

Q. If an impurity is present in a crystalline solid, then:

1. Melting point increases
2. Melting point decreases
3. Melting point does not change
4. Can't be predicted

Q. If NaCl is doped with ${10}^{-3}mol$% $SrC{l}_2$, then the concentration of cation vacancies will be

1. 1 x 10^-3 mol%
2. 2 x 10^-3 mol%
3. 3 x 10^-3 mol%
4. 4 x 10^-3 mol%

Q. Germanium or silicon becomes an extrinsic semiconductor due to which defect?

1. Schottky defect
2. Frenkel defect
3. Both A and B
4. Chemical impurity

Q. When $NaCl$ is doped with ${10}^{-5}$ moles % of $SrC{l}_2$, what is the number of cationic vacancies per mole?

1. ${10}^{-5}\times N_A$
2. ${10}^{-7}\times N_A$
3. $2\times {10}^{-7}{N}_A$
4. None of these

Q. In presence of impurities, the melting point of solid _____________.

1. increases
2. does not change
3. changes according to the weather
4. decreases

Q. Which of the following analogies is incorrect?
[0.77 Mark]

1. $NaCl$ : Ionic solid : : $Si{O}_2$ : Covalent solid
2. $NaCl$ : Schottky defect : : $ZnS$ : Frenkel defect
3. Frenkel defect : Density increases : : Schottky defect : Density decreases
4. FCC unitcell : $a=2\sqrt{2}r$ : : BCC unit cell : $a=\frac{4r}{\sqrt{3}}$

Q. How many $Cl$ atoms can you ionise in the process: $Cl⟶{Cl}^{+}+e$ by the energy liberated for the process $Cl+e⟶{Cl}^{-}$ for 1 mole atoms? Given; $IE=12.967eV$ and $EA=3.61eV$. If answer in multiple of $X\times {10}^{23}$, find the value of X to the nearest integer value.

Q. What are the types of defects are seen in solids? Write down with example

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

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

Q.

Impurity defect is the defect in which

1. Both cations and anions miss from their lattice sites creating voids.

2. Ions are replaced by different elements ions.

3. Anions occupy interstitial voids.

4. electrons occupy interstitial voids.

Q.

The incorrect statement in the following is

1. all the above

2. electrical neutrality is maintained in all types of defects

3. the density is less than pure crystal in Frenkel defect

4. Stoichiometry is maintained in Schottky defect

Q. In schottky deffect hole is created and in this hole other element can fit or not and fit then what are changes in propertys?

Q. Match the elements in List I with appropriate element in List II.

Q. Which is the set of nonstoichiometric compounds?

1. $NaCl,FeO,MgC{l}_2$
2. $FeO,CuS,VSe$
3. $CuCl,CuS,MgO$
4. $F{e}_3{O}_4,NaCl,Cus$

Q. The type of defect in solid is

1. Frenkel defect
2. Schottky defect
3. Metal excess defect
4. Impurity defect

Q. Blue colour of the sky is due to :

1. absorption of light by dust particles
2. reflection of light by dust particles
3. scattering of light by dust particles
4. presence of clouds

Q. If in Agcl crystal when cacl2 is added then schottky defect is observed----explain why?

Q. Thus, loss in weight on treatment with concentrated $H_{2}S{O}_4$ is due to :

1. $H_{2}O$ is lost due to absorption.
2. $C{l}^{-}$ to lost as HCl
3. $C{r}^{3+}$ is lost as $C{r}_2(S{O}_4{)}_3$
4. $C{l}^{-}$ and lost as $C{l}_2$