Solid State Test

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Solid State Test - 29

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Weekly Quiz Competition

Question 1
1 / -0

Iron occurs as bcc as well as fcc unit cell. If the effective radius of an atom of iron is $124$ pm, compute the density (in g cm $^{-3}$ ) of iron in bcc and fcc respectively :

A
$8.4,\ 9.8$

B
$9.3,\ 4.6$

C
$8.6,\ 7.9$

D
$7.9,\ 8.6$

Solution

The expression for density is as follows:

Density $=d = \dfrac{zM}{VN_o}$

For bcc, $z =2$

$a = \dfrac{4r}{\sqrt {3}}$

So, density $=\dfrac{ 2\times 56}{a^3(6\times 10^{23})} = 7.9$ g cm $^{-3}$

For fcc, $n =4$

$a = 2\sqrt {2} r$

So, density $= \dfrac{4\times 56}{a^3(6\times 10^{23})} = 8.6$ g cm $^{-3}$

Hence, the density of iron in bcc and fcc are $7.9$ g cm $^{-3}$ and $8.6$ g cm $^{-3}$ respectively.

Hence, the correct option is $\text{D}$
Question 2
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An element A (atomic weight $= 100$ amu) having bcc structure has unit cell edge length of $400$ pm. Calculate the density of A.

A
$2.59$ g cm $^{-3}$

B
$5.188$ g cm $^{-3}$

C
$10.37$ g cm $^{-3}$

D
None of the above

Solution

$density = \dfrac{zM}{N_o \times (a \times 10^{-10})^3}$

for bcc structure z= 2

$d = \dfrac{2 \times 100}{6 \times 10^{23} \times (400 \times 10^{-10})^3}$

$d= 5.188 \text{ g cm}^{-3}$

Hence, the correct option is $\text{B}$
Question 3
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Which one is an amorphous solid?

A
Diamond

B
Graphite

C
Common salt

D
Glass

Solution

Glass is an amorphous solid. It is called psuedo solid. Diamond, graphite and common salt are crystalline solids.
Question 4
1 / -0

A unit cell of sodium chloride has four formula units. The edge of length of the unit cell is $0.564$ nm. What is the density (in g cm $^{-3}$ ) of sodium chloride?

A
$1.5$

B
$2.0$

C
$2.2$

D
$3.2$

Solution

As we know, the expression for density is as follows:
Density $=d = \dfrac{nM}{VN_o}$ , where $n$ is the number of atoms and $M$ is the molecular mass.
For NaCl, $n =4$
Density $= \dfrac{4\times 58.5}{(0.564\times 10^{-9})^3(6\times 10^{23})} = 2.2$ g cm $^{-3}$
Question 5
1 / -0

Which of the following is not a crystalline solid?

A
Common salt

B
Sugar

C
Iron

D
Rubber

Solution

Common salt, sugar and iron are crystalline solids whereas rubber is an amorphous solid as it does not have well developed perfectly ordered crystalline structure. Other amorphous solids include tar, glass, plastic, butter etc.

Hence, the correct option is $\text{D}$
Question 6
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The lattice parameters, $a\neq b\neq c$ and $\alpha=\gamma=90^{\circ},\,\beta\neq 90^{\circ}$ represents a :

A
tetragonal system

B
orthorhombic system

C
monoclinic system

D
triclinic system

Solution

The axial distances and the axial angles, $a\neq b\neq c$ and $\alpha=\gamma=90^{\circ},\,\beta\neq 90^{\circ}$ represents a monoclinic system.

None of the edge lengths is equal to each other.

Two of the angles are equal to each other and equal to $90^0$ . One of the angles is not equal to $90^0$ .

Example of triclinic crystal systems is $Na_2SO_4.10H_2O$ .

Hence, the correct option is $\text{C}$
Question 7
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Which of the following is an amorphous substance?

A
Zinc

B
Clay

C
Salt

D
Sugar

Solution

Amorphous solids are a type of solids that lacks definition in shape, pattern and long range order as well as do not have a well defined melting point.

Answer: (B) Clay
Question 8
1 / -0

Potassium crystallizes in a body-centered cubic lattice with edge length aequal to 5.2 $\mathring A$ , what is the calculated density (in g cm $^{-3}$ ) of crystalline potassium ?

A
$2.2$

B
$1.9$

C
$0.92$

D
None of the above

Solution

As we know, density $=d= \dfrac{nM}{VN_o}$
Here, $n= 2$

$d = \dfrac{2\times 39}{(a)^3(N_o)}=0.92$ g cm $^{-3}$
Question 9
1 / -0

The most unsymmetrical crystal system is:

A
cubic

B
hexagonal

C
triclinic

D
orthorhombic

Solution

The most unsymmetrical crystal system is triclinic while the most symmetrical crystal system is cubic.

The axial distances and the axial angles, $a\neq b\neq c$ and $\alpha\neq\beta\neq\gamma\neq 90^{\circ}$ represents triclinic system.

None of the edge lengths is equal and none of the angles is equal to each other. Also, none of the angles is equal to $90^0$ .

Examples of triclinic crystal systems include $K_2Cr_2O_7$ and $H_3BO_3$ .

Hence, the correct option is $\text{C}$
Question 10
1 / -0

A pseudo solid is:

A
glass

B
pitch

C
KCl

D
glass and pitch both

Solution

Pseudo solids (such as glass & pitch) lack a regular three-dimensional arrangement of atoms.
Pitch is a viscoelastic polymer which can be natural or manufactured, derived from petroleum.
Solids are most stable in crystalline form. However, if a solid is formed rapidly (for example, when a liquid is cooled suddenly), its atoms or molecules do not have time to align themselves and may become locked in positions other than those of a regular crystal. Such resulting solids are called Pseudo solids.

Hence, the correct option is $\text{D}$

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Solid State Test - 29

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Solid State Test - 29

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Question 1

8.4, 9.88.4,\ 9.88.4, 9.8

9.3, 4.69.3,\ 4.69.3, 4.6

8.6, 7.98.6,\ 7.98.6, 7.9

7.9, 8.67.9,\ 8.67.9, 8.6

Solution

Question 2

2.592.592.59 g cm−3^{-3} −3

5.1885.1885.188 g cm−3^{-3} −3

10.3710.3710.37 g cm−3^{-3} −3

None of the above

Solution

Question 3

Diamond

Graphite

Common salt

Glass

Solution

Question 4

1.51.51.5

2.02.02.0

2.22.22.2

3.23.23.2

Solution

Question 5

Common salt

Sugar

Iron

Rubber

Solution

Question 6

tetragonal system

orthorhombic system

monoclinic system

triclinic system

Solution

Question 7

Zinc

Clay

Salt

Sugar

Solution

Question 8

2.22.22.2

1.91.91.9

0.920.920.92

None of the above

Solution

Question 9

cubic

hexagonal

triclinic

orthorhombic

Solution

Question 10

glass

pitch

KCl

glass and pitch both

Solution

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$8.4,\ 9.8$

$9.3,\ 4.6$

$8.6,\ 7.9$

$7.9,\ 8.6$

$2.59$ g cm $^{-3}$

$5.188$ g cm $^{-3}$

$10.37$ g cm $^{-3}$

$1.5$

$2.0$

$2.2$

$3.2$

$2.2$

$1.9$

$0.92$