Frenkel Defect

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. 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.

Arrange in order of increasing dipole movement.

I. Toulene

II. m - dichlorobenzene

III. o - dichlorobenzene

IV. p - dichlorobenzene

1. $I<IV<II<III$

2. $IV<I<II<III$

3. $IV<I<III<II$

4. $IV<II<I<III$

Q.

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

__

Q. Given below are two statements : One is labelled as Assertion A and other is labelled as Reason R.

Assertion A : The dihedral angles in $H_2{O}_2$ in gaseous phase is ${90.2}^{\circ }$ and in solid phase is ${111.5}^{\circ }$.
Reason R : The change in dihedral angle in solid and gaseous phase is due to the difference in the inter molecular forces.

Choose the most appropriate answer from the options given below for A and R.

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Q. Due to Frenkel defect the density of ionic solids

1. Decreases

2. Increases

3. Does not change

4. Changes

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

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

Q. An ionic solid $A^{\oplus }{B}^{\ominus }$ crystallises in a bcc lattice. The distance between a cation and an anion in the lattice is 338 pm. The edge length of cell is:

1. 338 pm
   
2. 390.3 pm
   
3. 292.7 pm
   
4. 507 pm

Q.

Assertion: Frenkel defect doesn’t have any effect on density of the crystal.

Reason: Dislocated cation occupies the interstitial site

1. 1 is correct, 2 is correct and 2 is correct explanation of 1

2. 1 is correct, 2 is correct and 2 is not correct explanation of 1

3. 1 is correct, 2 is wrong

4. 1 is wrong, 2 is correct

Q. Which one of the following crystals does not exhibit Frenkel defect

1. AgBr
2. AgCl
3. KBr
4. ZnS

Q.

Frenkel defect is caused due to

[MP PET 1994]

1. An ion missing from the normal lattice site creating a vacancy
2. An extra positive ion occupying an interstitial position in the lattice
3. An extra negative 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. A solid made up of ions of A and B possess edge length of unit cell of 0.564 nm has four formula units. Among the two ions the smaller ones occupy the interstitial void and the larger ions occupy the space lattice with ccp type of arrangement. The solid has more tendency to show Frenkel defect than schottky defect. (assume anion in contact)

The packing fraction of the solid is :

1. 79.25%
2. 74%
3. 80.1%
4. 74.9%

Q.

Match the following

1. Schottky defect

2. Frenkel defect a) Conduction increases

3. Vacancy defect b)Conduction Decreases

4. Interstitial defect c) Conduction Remains same

1. 1-a, 2-b, 3-a, 4-b

2. 1-a, 2-a, 3-a, 4-a

3. 1-a, 2-c, 3-a, 4-b

4. 1-b, 2-b, 3-a, 4-b

Q.

Due to Frenkel defect, the density of ionic solids

[MP PET 1996; MP PMT 2002]

1. Increases

2. Decreases

3. Does not change

4. Changes

Q. Which of the following statements is not correct?
(AIPMT-2008)