Solid State Test

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Solid State Test - 36

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Weekly Quiz Competition

Question 1
1 / -0

Which kind of point defect is found in KCl crystal?

A
Frenkel

B
Schottky

C
Linear

D
Impurity

Solution

In ionic crystals, the defect forms when oppositely charged ions leave their lattice sites, creating vacancies. These vacancies are formed in stoichiometric units, to maintain an overall neutral charge in the ionic solid. The vacancies are then free to move about as their own entities. Normally these defects will lead to a decrease in the density of the crystal. It is found in crystals of $$KCl$$ , $$NaCl$$ etc.
Question 2
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A metal has bcc structure and the edge length of its unit cell is $$3.04\dot{A}$$. The volume of the unit cell in $$cm^{3}$$ will be :

A
$$1.6\times 10^{21}cm^{3}$$

B
$$2.81\times 10^{-23}cm^{3}$$

C
$$6.02\times 10^{-23}cm^{3}$$

D
$$6.6\times 10^{-24}cm^{3}$$

Solution

Volume of unit cell $$\left ( V \right )=a^{3}$$
$$\therefore =\left ( 3.04\times 10^{-8}cm \right )^{3}$$
$$= 2.81\times 10^{-23}cm ^{3}$$
Question 3
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The crystal lattice of NaCl is :

A
Face-centered Cubic lattice

B
Body-centered cubic lattice

C
Simple cubic lattice

D
Hexagonal close packing

Solution

The crystal lattice of $$NaCl$$ is face -centered cubic.
Question 4
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Which metal among the followings has the highest packing efficiency?

A
Iron

B
Tungsten

C
Aluminium

D
Polonium

Solution

The packing efficiency is the fraction of volume in a crystal structure that is occupied by constituent particles (volume of space occupied by the spheres/total volume). The majority of metals take on either the hcp or bcc structure. Among the given metals $$Al$$ occupies hexagonal close-packed (hcp) is having 0.74 packing efficiency and other metals form body-centered cubic (bcc) which has 0.68 packing efficiency.
Thus, Aluminium has the highest packing efficiency in comparison to Iron, Tungsten and Polonium.
Hence (C) is correct answer.
Question 5
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Liquid crystal phase which are more close to the solid than to liquid is :

A
Nematic

B
Smectic

C
Lyotropioc

D
Cholesteric

Solution

There are 4 types of phases present in Liquid crystal phases. Smectic phase is more close to solid than liquid because of its atomic arrangement.

Hence, option B is correct.
Question 6
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Which of the following is correct regarding defect in solid?

A
Schottky defect has no effect on the physical properties of solids

B
Frenkel defect is usually favoured by a very small difference in the sizes of cations and anions

C
Frenkel defect is a dislocation defect

D
Trapping of protion in the lattice leads to the formation of F-centres

Solution

The Schottky defect has some effect on the physical properties of solids such as lower density, lower lattice energy or stability etc.
Frenkel defect is usually favoured by a large difference in the sizes of cations and anions. Cations are small in size than anions.
Frenkel defect is a dislocation defect. A cation moves to another position between two layers.
Trapping of electrons in the lattice leads to the formation of F-centers

Hence, the correct option is $$\text{C}$$
Question 7
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Which of the following crystal has unit cell such that $$a\neq b \neq c$$ and $$\alpha\neq \beta\neq \gamma \neq 90^o?$$

A
$$KNO_3$$

B
$$K_2SO_4$$

C
$$K_2Cr_2O_7$$

D
$$NaNO_3$$

Solution

$$\displaystyle K_2Cr_2O_7$$ has $$\displaystyle \text{triclic}$$ unit cell such that
$$\displaystyle a\neq b \neq c$$ and $$\displaystyle \alpha\neq \beta\neq \gamma \neq 90^o$$.

Hence, the correct option is $$\text{C}$$
Question 8
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In face centred cubic unit cell, what is the volume occupied?

A
$$\dfrac{4}{3}\pi r^3$$

B
$$\dfrac{8}{3}\pi r^3$$

C
$$\dfrac{16}{3}\pi r^3$$

D
$$\dfrac{64 r^3}{3\sqrt{3}}$$

Solution

In fcc unit cell, no. of atoms are $$=[6 \times \dfrac{1}{2}] + [8 \times \dfrac{1}{8}] = 4$$

Volume of 1 spherical atom is $$\dfrac { 4 }{ 3 } \pi { r }^{ 3 }$$.

So, volume occupied by atoms in fcc unit cell will be $$4\times \dfrac { 4 }{ 3 } \pi { r }^{ 3 }=\dfrac { 16 }{ 3 } \pi { r }^{ 3 }$$, where, r is radius of atom.

Hence, the correct option is $$\text{C}$$
Question 9
1 / -0

Which metal crystallises in a simple cubic structure?

A
Polonium

B
Copper

C
Nickel

D
Iron

Solution

$$\displaystyle Polonium$$ crystallises in a simple cubic structure.
$$\displaystyle Copper$$ and $$\displaystyle Nickel$$ crystallises in a face centred cubic structure.
$$\displaystyle Iron$$ crystallises in a body centred cubic structure.
Question 10
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In a face centred cubic arrangement of A and B atoms in which 'A' atoms are at the corners of the unit cell and 'B' atoms are at the face centres. One of the 'A' atom is missing from one corner in unit cell. The simplest formula of compound is :

A
$$A_7B_3$$

B
$$A_7B_8$$

C
$$AB_3$$

D
$$A_7B_{24}$$

Solution

In a face centred cubic arrangement of A and B atoms in which 'A' atoms are at the corners of the unit cell.

There are total 8 corners and each contributes one eight to the unit cell.

One of the 'A' atom is missing from one corner in unit cell.

So there are 7 'A' atoms with total contribution $$\displaystyle 7 \times \dfrac {1}{8} = \dfrac {7}{8}$$.

'B' atoms are at the face centres. There are six face centres. Each contributes one half to the unit cell.

Total contribution $$\displaystyle = 6 \times \dfrac {1}{2}=3$$
$$\displaystyle A: B = \dfrac {7}{8} : 3 = 7 : 24$$

The simplest formula of compound is $$\displaystyle A_7B_{24}$$

Hence, the correct option is D.

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Solid State Test - 36

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Solid State Test - 36

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Question 1

Frenkel

Schottky

Linear

Impurity

Solution

Question 2

$$1.6\times 10^{21}cm^{3}$$

$$2.81\times 10^{-23}cm^{3}$$

$$6.02\times 10^{-23}cm^{3}$$

$$6.6\times 10^{-24}cm^{3}$$

Solution

Question 3

Face-centered Cubic lattice

Body-centered cubic lattice

Simple cubic lattice

Hexagonal close packing

Solution

Question 4

Iron

Tungsten

Aluminium

Polonium

Solution

Question 5

Nematic

Smectic

Lyotropioc

Cholesteric

Solution

Question 6

Schottky defect has no effect on the physical properties of solids

Frenkel defect is usually favoured by a very small difference in the sizes of cations and anions

Frenkel defect is a dislocation defect

Trapping of protion in the lattice leads to the formation of F-centres

Solution

Question 7

$$KNO_3$$

$$K_2SO_4$$

$$K_2Cr_2O_7$$

$$NaNO_3$$

Solution

Question 8

$$\dfrac{4}{3}\pi r^3$$

$$\dfrac{8}{3}\pi r^3$$

$$\dfrac{16}{3}\pi r^3$$

$$\dfrac{64 r^3}{3\sqrt{3}}$$

Solution

Question 9

Polonium

Copper

Nickel

Iron

Solution

Question 10

$$A_7B_3$$

$$A_7B_8$$

$$AB_3$$

$$A_7B_{24}$$

Solution

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