Frenkel Defect

Q.

A diatomic molecule $X_2$ has a body-centred cubic ($\mathrm{bcc}$) structure with a cell edge of $300pm$. The density of the molecule is $6.17g/c{m}^{-1}$. The number of molecules present in $200g$ of $X_2$ is: (Avogadro constant $\left(N_A\right)=6.023\times {10}^{23}$)

1. $8N_A$

2. $2N_A$

3. $40N_A$

4. $4N_A$

Q.

Which one of the following crystals does not exhibit Frenkel defefect

1. AgBr

2. ZnS

3. AgCl

4. KBr

Q.

Explain the following terms with suitable examples:

(i) Schottky defect

(ii) Frenkel defect

(iii) Interstitials and

(iv) F-centres

Q.

In interstitial defect, since constituent particles occupy interstitial site then why there is an increase in density?

Q. What is the defect exhibted by the ionic crystal when the difference in the size of cations and anions is large?

1. Defectless crystal
2. Schottky defect
3. Frenkel defect
4. Both Schottky and Frenkel defects

Q. Which type of defect has the presence of cations in interstitial sites?

1. Metal deficiency defect
2. Schottky defect
3. Vacancy defect
4. Frenkel defect

Q.

Which of the following defects is also known as dislocation defect ?

(a) Frebkel defect (b) Schottky defect

(c)Non-stoichiometric defect (d)Simple interstitial defect

Q.

Which of the following point defects are shown by AgBr(s) crystals ?

1. Schottky defect

2. Frenkel defect

3. Metal excess defect

4. Metal deficiency defect

(a) 1 and 2 (b) 3 and 4 (c) 1 and 3 (d) 2 and 4

Q.

Frenkel defect is also Known as ................

(a) stoichiometric defect (b) dislocation defect

(c) impurity defect (d) non-stoichiometric defect

Q.

What is the color of ferrous sulfate crystals?

Q.

what are the importance if coordination compounds?

Q. Crystals can be classified into ___ basic crystal lattices.

1. 3
2. 7
3. 14
4. 4

Q. Which is the incorrect statement?

1. $Fe{O}_{0.98}$ has non stoichiometric metal deficiency defect
2. Density decreases in case of crystals with Schottky’s defect
3. Frenkel defect is favoured in those ionic compounds in which sizes of cation and anions are almost equal
4. $NaC{l}_{\left(s\right)}$ is an insulator, $Si$ is a semiconductor, $Ag$ is a conductor, quartz is a piezo electric crystal

Q. In a solid lattice, the cation has left a lattice site and is located at interstitial position, the lattice defect is:

1. Interstitial defect
2. Vacancy defect
3. Frenkel defect
4. Schottky defect

Q.

Which one of the following has Frenkel defect

[MP PMT 2000]

1. Sodium chloride

2. Graphite

3. Silver bromide

4. Diamond

Q. Which of the following statements is/are true ?
i) Density of solid gets increased due to interstitial defects
ii) Frenkel defects do not alter the density of the solid
iii) Non-stoichiometric defects modify the formula of the compound

iv) Non-stoichiometric defects do not alter the density of the solid

1. i, ii & iii

2. ii & iii

3. i, iii & iv

4. i& iii

Q.

AgBr shows both schottky and frenkel defect why?

Q.

What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

Q. On heating a crystal of KCl in potassium vapour the crystal starts exhibiting a violet colour. Why

Q.

Cations are present in the interstitial sites in ...........

(a) Frenkel defect (b) Schottky defect

(c) vacancy defect (d) metal deficiency defect

Q.

In the laboratory, sodium chloride is made by burning the sodium in the atmosphere of chlorine which is yellow in colour. The cause of yellow colour is

1. Presence of N^a+ ions in the crystal lattice
2. Presence of Cl^- ions in the crystal lattice
3. Presence of face centered cubic crystal lattice
4. Presence of electron in the crystal lattice

Q.

The defect when an ion leaves its lattice point and occupies an interstitial position in the crystal lattice is called ------------------

__

Q.

How are vacancy defects stoichiometric defects if some atoms are absent? Wouldn't that change the stoichiometry of the compound?

Q.

Frenkel defect is caused due to

[MP PET 1994]

1. An extra negative ion occupying an interstitial position in the lattice
2. An ion missing from the normal lattice site creating a vacancy
3. An extra positive ion occupying an interstitial position in the lattice
4. The shift of a positive ion from its normal lattice site to an interstitial site

Q.

When an ion leaves its correct lattice site and occupies interstitial sites in its crystal lattice, it is called

1. Crystal defect

2. Frenkel defect

3. Schottky defect

4. None

Q. In AgBr crystal, the ion size lies in the order $A{g}^{+}<<B{r}^{-}$. On the basis of the given information only, the AgBr crystal should have the following characteristics

1. Defectless (perfect) crystal
2. Schottky defect only
3. Frenkel defect only
4. Both Schottky and Frenkel defects

Q. Are F-centres also seen in metal excess defect due to extra cations ?

Q. White ZnO (s) becomes yellow upon heating due to

1. Creation of F-centers
2. Addition of electrons
3. Creation of Frenkel defect
4. All of the above

Q. In $AgCl$, the $A{g}^{+}$ ions are displaced from their lattice position to an interstitial position. Such a defect is called:

1. None of these
2. Frenkel defect
3. Schottky defect
4. Colour centre

Q. ZnO shows yellow colour on Heating due to:

1. d-d transition
2. C-T spectra
3. Higher polarisation caused by $Z{n}^{2+}$ ion
4. F-centres