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This mock test of Crystals NAT Level – 2 for Physics helps you for every Physics entrance exam.
This contains 10 Multiple Choice Questions for Physics Crystals NAT Level – 2 (mcq) to study with solutions a complete question bank.
The solved questions answers in this Crystals NAT Level – 2 quiz give you a good mix of easy questions and tough questions. Physics
students definitely take this Crystals NAT Level – 2 exercise for a better result in the exam. You can find other Crystals NAT Level – 2 extra questions,
long questions & short questions for Physics on EduRev as well by searching above.

*Answer can only contain numeric values

QUESTION: 1

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

Solution:

E - E_{f }= 0.2 eV

k_{B} = 8.62 x 10^{-5 }e**VK**^{-1}

T = 700**K
**

P = 0.036

The correct answer is: 0.036

*Answer can only contain numeric values

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 10^{29} m^{-3} .

Solution:

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

*Answer can only contain numeric values

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 10^{3} kg/m^{3} and its atomic mass is 1.05 x 10^{-25} kg).

Solution:

The correct answer is: 74

*Answer can only contain numeric values

QUESTION: 4

Consider a crystal of fee structure. The density of the crystal is 8.96 glcm^{3} and atomic weight is 63.5. Then what is the lattice constant for the crystal (in )?

Solution:

Lattice constant

The correct answer is: 3.61

*Answer can only contain numeric values

QUESTION: 5

The distance between the adjacent atomic planes in CaCO_{3} is 0.3 nm. The smallest angle of Bragg scattering for 0.03 nm X -ray is (in degrees)

Solution:

**- 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

QUESTION: 6

Sodium contains 2.54 x10^{22} free electrons per cm^{3} ( given = 6.63 x 10 ^{-34} J-s, m= 9 .11 x 10^{-31} kg , k_{B} = 1.38 x 10^{-23 }JIK and 1eV = 1.6 x 10^{-19 }J ) , then Fermi D 4 temperature is given in terms of 10^{4} K as?

Solution:

We know that

⇒

The correct answer is: 3.6

*Answer can only contain numeric values

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)

Solution:

For 2nd peak [2 0 0],

The correct answer is: 35.3

*Answer can only contain numeric values

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?

Solution:

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

QUESTION: 9

Given that density of sodium is 0.971 g/cm^{3} 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 10^{23} atoms/mol. Assuming each sodium atom contribute one electron to the electron gas. What is the electron density in units of 10^{28} Im^{3} ?

Solution:

Electron density of sodium

The correct answer is: 2.54

*Answer can only contain numeric values

QUESTION: 10

Packing fraction of diamond cubic crystal structure is ____ % ?

Solution:

Number of atoms in diamond crystal

Packing fraction

= 0.34

= 34%

The correct answer is: 34

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