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Crystals NAT Level – 2 - Physics MCQ


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10 Questions MCQ Test - Crystals NAT Level – 2

Crystals NAT Level – 2 for Physics 2024 is part of Physics preparation. The Crystals NAT Level – 2 questions and answers have been prepared according to the Physics exam syllabus.The Crystals NAT Level – 2 MCQs are made for Physics 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Crystals NAT Level – 2 below.
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*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 1

The probability that a state which is 0.2eV above the fermi energy in a metal atom at 700K is?


Detailed Solution for Crystals NAT Level – 2 - Question 1

E - Ef = 0.2 eV
kB = 8.62 x 10-5 eVK-1
T = 700K

P = 0.036
The correct answer is: 0.036
 

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 2

Be has hexagonal closed packed structure with smaller lattice parameter equal to 2.29. Concentration of electron in Be crystal is in terms of 1029 m-3 .


Detailed Solution for Crystals NAT Level – 2 - Question 2

Here a = 2.29 
for hexagonal close packing

There are two atoms in primitive cell and each atom carries 4 electrons.

The correct answer is: 8.15

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*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 3

A copper wire of uniform cross-sectional area 10 x 10-6 m-2 carries a current of 1 Assuming that each copper atom contributes one electron to the electron gas, the drift velocity of free electron in units of µm/sec is :
 of copper is 8.94 x 103 kg/m3 and its atomic mass is 1.05 x 10-25 kg).


Detailed Solution for Crystals NAT Level – 2 - Question 3


The correct answer is: 74

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 4

Consider a crystal of fee structure. The density of the crystal is 8.96 glcm3 and atomic weight is 63.5. Then what is the lattice
constant for the crystal (in )?


Detailed Solution for Crystals NAT Level – 2 - Question 4

Lattice constant 


The correct answer is: 3.61

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 5

The distance between the adjacent atomic planes in CaCO3 is 0.3 nm. The smallest angle of Bragg scattering for 0.03 nm X -ray is (in degrees)


Detailed Solution for Crystals NAT Level – 2 - Question 5

- For constructive interference, we must have                 

2dsinθ=nλ

 sinθ=nλ/2d

=1×0.3×10−10 / 2×0.3×10-9

                =0.05rad

 or            

=0.05×180/π = 2.86degree

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 6

Sodium contains 2.54 x1022   free electrons per cm3 ( given = 6.63 x 10 -34 J-s, m= 9 .11 x 10-31 kg , kB = 1.38 x 10-23 JIK and 1eV = 1.6 x 10-19 J ) , then Fermi D 4 temperature is given in terms of 104 K as?


Detailed Solution for Crystals NAT Level – 2 - Question 6

We know that 

⇒ 

The correct answer is: 3.6

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 7

In a powder diffraction pattern recorded from a face-centred cubic sample using X- rays. The first peak appears at 30°. The second peak will appear at what angle (degrees)


Detailed Solution for Crystals NAT Level – 2 - Question 7


For 2nd peak [2 0 0],

The correct answer is: 35.3

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 8

Masses of ionic radii of Na+ and CI– in NaCI crystals are 22.99 amu, 0.98A and 35.45 amu, 1.82A respectively. What is the packing fraction of NaCI?


Detailed Solution for Crystals NAT Level – 2 - Question 8

Lattice parameter a = 
a = 2 [0.98 + 1.82] 
a = 5.6A
Each unit cell contains 4 atoms.
Packing fraction = 
Packing fraction = 
Packing fraction = 0.66
The correct answer is: 0.66

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 9

Given that density of sodium is 0.971 g/cm3 and atomic weight is 23. If h = 6.63 * 10¯34 Js, mass of electron = 9.11 x 10-31 kg and Avogadro’s number is 6.02 x 1023 atoms/mol. Assuming each sodium atom contribute one electron to the electron gas. What is the electron density in units of 1028 Im3 ?


Detailed Solution for Crystals NAT Level – 2 - Question 9

Electron density of sodium  

The correct answer is: 2.54

*Answer can only contain numeric values
Crystals NAT Level – 2 - Question 10

Packing fraction of diamond cubic crystal structure is ____ % ?


Detailed Solution for Crystals NAT Level – 2 - Question 10

Number of atoms in diamond crystal
Packing fraction 

= 0.34
= 34%
The correct answer is: 34

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