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UNIT 4: CRYSTAL STRUCTURE AND X-RAYS

1) Atomic Packing factor for FCC structure is

a) 0.52 b) 0.68 c) 0.74 d) 0.1
Ans c
2) The relation between atomic radius r and lattice constant a for the BCC
structure is
a) a=2r b) a= 4r/root 3 c) a=root 3r/4
Ans c
3) The Miller Indices ( hkl )represents
a) The direction b) a plane c) a set of parallel planes
Ans c
4) X-rays can be deflected by
a) Electric Field

b) Magnetic Field

c) Both Electric and Magnetic field

d) Neither due to electric nor due to magnetic field

Ans d
5) The coordination number of BCC structure is
a) 6 b) 8 c) 12
Ans b
6) Effective number of atoms for the unit cell of FCC structure is
a) 6 b) 2 c) 4
Ans c
7) Miller Indices of the plane parallel to Y and Z axes are
a) (100) b) (010) c) (001)
Ans a
8) The number of atoms per unit cell for non-primitive unit cell is
a) 2 b) 4 c) both
Ans a
9) The number of atoms per unit cell for a primitive unit cell
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a) 2 b) 1 c) 3
Ans b
10) The planes (224) and (448) are
a) Parallel to each other b) Perpendicular to each other c) None
Ans a
11) The packing density for BCC structure is
a) 0.68 b) 0.52 c) 0.74
Ans a
12) The coordination number for FCC structure is
a) 4 b) 8 c) 12 d) 6
Ans c
13) An X-ray has a wavelength of 0.01A0. Find its momentum
a) 6.6×10-22kg m/s b) 3.4×10-25kg m/s c)2.12 ×10-23kg m/s
Ans a
14) The packing fraction of diamond crystal is
a) 74 % b) 68 % c) 52 % d) 34 %
Ans a
15) Lattice constant for copper is 0.39 nm. The distance between (221) plane is
a) 0.08 nm b) 0.13 nm c) 0.43 nm d) 1.95 nm
Ans b
16) Which of the following wavelengths fall in the X-ray region
a) 10-4 cm

b) 10 A0

c) 1 A0

d) 104 A0

Ans c
17) Repeatable entity of a crystal structure is known is
a) Crystal b) Lattice c) Unit Cell d) Miller Indices
Ans c

18) X-rays were invented in the year

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a)1920

b) 1890

c) 1895

d) 1900

Ans c

19) X-rays were invented by the scientist

a) Newton

b) Goldstein

c) Bragg

d) Rontgen

Ans.d

20) The quality of X-rays depends upon

a) speed of the X-rays

b) penetrating power of X-rays

c)The K.E. of the X-rays

d) applications of the X-rays

Ans.b

21) When fast moving electrons hit the target,about 80% energy is used to melt the
target and remaining energy is converted into invisible rays of very short wavelength

Called as

a) Cathode rays

b) Positive rays
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c) X-rays

d) γ rays

Ans.c

22) In characteristics X-ray spectra the wavelength of x-rays depend upon

a) Target material

b) Velocity of striking electrons

c) vibrational energy of electrons

d) spin of the electrons

Ans.a

23) In continuous X-ray spectra, the wavelength of X-rays is inversely propotional to

a) K.E. of electrons

b) the applied potential

c) P.E. of target material

d) rotational energy

Ans b

24) The characteristics X-ray spectra depend upon

a) Target material

b) Jumping of electrons from higher shell to the lower shell

c) The frequency of the striking electron

d) the K.E. of the electrons

Ans a

25) X-rays are emitted when

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a) High energy electrons hit the substance of low molecular weight

b) High energy electrons hit a substance of high molecular weight

c) low energy electrons hit any substance

d) Low energy electrons hit a substance of high molecular weight

Ans.b

26) Which of the following can not be deflected by a magnat

a) positive rays

b) cathode rays

c) X-rays

d) Beta rays

Ans.c

28) On increasing the number of electrons striking the anode of an X-ray tube which
of the following characteristics of the X-ray increase?

a) Frequency

b) Intensity

c) Wavelength

d) power

Ans.b

29) Wavelength of visible light is more than that of X-rays ,What is the velocity of X-
rays in vaccum?

a) Less than velocity of light

b) Greater than velocity of light

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c) Same as velocity of light

d) Sometimes less and sometimes greater than velocity of light

Ans.c

30) X-rays and γ rays are both electromagnetic waves .Which of the following
statement is true?

a) In general X-rays have larger wavelength than of γ rays

b) Wavelength and frequency of X-rays are both that of γ rays

c) X-rays have smaller wavelength than that of γ rays

d) γ rays have smaller frequency than that of X-rays

Ans a

31) Charactristics or line X-ray spectra are not excited by which one of the following

a) Neutron bombardment

b) Proton bombardment

c) α ray absorption

d) Electron bombardment

Ans.c

32) The continuous X-ray spectra produced by an X-ray machine at constant voltage
has which of the following

a) Maximum wavelength

b) minimum wavelength

c) minimum frequency

d) single wavelength
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Ans.b

33) What happens when fast moving electrons are stopped and fall on the metallic
target in an evacuated glass bulb

a) γ rays are produced

b) X rays are produced

c) β rays are produced

d) Reflected back

Ans.b

34) Which of the following wavelength falls in X-ray region?

a)10-4A0

b) 1 A0

c) 1000 A0

d)10000 A0

Ans b

35) The wavelength of X-rays in the order of

a)cm

b) micron(10-6 m)

c) Angstrom(10-10m)

d)meter

Ans.c
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36) When a beam of accelerated electron hit a target a continuous X-ray spectrum is
emitted from the target ,Which of the following wavelength is absent in the X-ray
spectrum if the X-ray tube is operating at 40000 V

a) 1.5 A0

b) 0.5 A0

c) 0.25 A0

d) 1.0 A0

Ans c

37) An X-ray has a wavelength of 0.010 A0,its momentum is

a) 2.126×10-23kg.m/sec

b) 3.313×10-22kg.m/sec

c) 3.456×10-25kg.m/sec

d)6.626×10-22kg.m/sec

Ans.d

38) In producing X-ray beam of electrons accelerated by a potential difference V

are made to strike a metal target. For what value of V of the following X-rays

have the lowest wavelength.Useλmin=0.3094 A0

a) 40 KV
b) 30 KV
c) 20 KV
d) 10 KV ( Hint V=12415/ λmin)

Ans.a

39. In FCC crystal structure the atomic radius is

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√2 √5 √3 𝑎
a) r = a b) r = 4 a c) r = 4 a d) r = 2
4
Ans: a)
40. The Miller Indices of the following plane is
a) 100 b) 101 c) 111 d) 010
Ans: c)
41. X-ray is ---------- charge particle?
a) Positively
b) Negatively
c) Both Positive & Negative
d) Charge less
Ans: d)
42. The wavelength of X-ray is in the range of
a) 0.1 to 100 A° b) 0.1 to 100 μm
c) 0.1 to 100 mm d) None of above
Ans: a)

43. In BCC crystal structure the atomic radius is

√2 √5 √3 𝑎
a) r = 4 a b) r = 4 a c) r = 4 a d) r = 2
Ans: c)
44. The Miller Indices of the following plane is
a) 100 b) 101 c) 001 d) 010
Ans: b)
45. X-ray is
a) Electromagnetic wave
b) Sound wave
c) Ultrasonic wave
d) Matter wave
Ans: a)
46. In SC crystal structure the atomic radius is
√2 √5 √3 𝑎
a) r = 4 a b) r = 4 a c) r = 4 a d) r = 2
Ans: d)
47. Number of atoms per unit cell for Simple Cubic structure is
a) 1 b) 2 c) 4 d) None of above
Ans: a)
48. If the lattice constant of cubic crystal is 3A0, find the interplaner spacing between (111)
plane.
a) 2.64 A0 b) 3.56 A0 c) 4.09 A0 d) 3A0
Ans: d)
49. Na has BCC structure with lattice constant 4.29 A0. Calculate the interplaner spacing for
(123) plane.
a) 1.146 A0 b) 1.01A0 c) 3.05 A0 d) 4.29 A0
Ans: a)
50. Na has BCC structure with lattice constant 4.29 A0. Calculate the interplaner spacing for
(330) plane.
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a) 1.146 A0 b) 1.01A0 c) 3.05 A0 d) 4.29 A0

Ans: b)
51. The Miller indices for set of parallel planes are
a) Different b) zero c) same d) none of above
Ans: c)
52. Number of atoms per unit cell for Body centered Cubic structure is
a) 1 b) 2 c) 4 d) None of above
Ans: b)

53. Number of atoms per unit cell for Face centered Cubic structure is
a) 1 b) 2 c) 4 d) None of above
Ans: c)
54. Co-ordination Number for Simple Cubic structure is
a) 6 b) 8 c) 12 d) None of above
Ans: a)
55. Co-ordination Number for Body centered Cubic structure is
a) 6 b) 8 c) 12 d) None of above
Ans: b)
56. Co-ordination Number for Face centered Cubic structure is
a) 6 b) 8 c) 12 d) None of above
Ans: c)
57. Atomic packing factor (APF) for Simple Cubic structure is
a) 52% b) 68% c) 74% d) None of above
Ans: a)
58. Atomic packing factor (APF) for Body centered Cubic structure is
a) 52% b) 68% c) 74% d) None of above
Ans: b)
59. Atomic packing factor (APF) for Face centered Cubic structure is
a) 52% b) 68% c) 74% d) None of above
Ans: c)
60. The minimum wavelength of X-rays in continuous spectrum is --------- proportional to
potential difference between cathode and anode.
a) Directly proportional b) Inversely proportional
c) Equal d) None of above
Ans: b)
61. In continuous spectrum wavelength of X-rays is Inversely proportional to
a) Voltage b) Atomic Mass c) target material d) None of above
Ans: a)
62. X-rays are deflected in
a) Only Electric field b) only Magnetic field c) Both d) Not Deflected
Ans: d)
63. Calculate the wavelength of x-rays when a potential difference of 30 KV is applied between
filament and anode.
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a) 0.86 A0 b) 0.41 A0 c) 0.30 A0 d) 0.62 A0

Ans: b
64. Find the minimum wavelength when an x-ray tube works on 50000 volts
a) 0.248 A0
b) 0.41 A0
c) 0.39 A0
d) 0.526 A0
Ans: a
65. The only element exhibiting simple cubic structure is
a) Silver
b) Polonium
c) Zinc
d) Diamond
Ans: b
66. The void space in simple cubic structure is
a) 48 c) 52
b) 23 d) 50
Ans: a
67. The void space in Body centered cubic structure is
a) 48 c) 32
b) 23 d) 50
Ans: c
68. The void space in Face centered cubic structure is
a) 26 c) 32
b) 23 d) 50
Ans: a
69. Relation between density and lattice constant is
 M 
1/3 1/3
 nM 
a) a=  c) a =  
 N   Nn 
 n    
1/3 1/3

b) a =   d) a =  
 NM   NM 
Ans: a
70. Nickel is characterised by FCC lattice. The edge of the unit cell is 3.52 A0 . The atomic
weight of nickel is 56.71. Determine the density of the metal.
a) 8639.63kg / m3 c) 639.63kg / m
3

b) 69.63kg / m3 d) 102.63kg / m
3

Ans: a
71. A substance with face centered cubic lattice has density 6250 kg/m3 and molecular weight
60.2. Calculate the lattice constant a. Given Avogadro number 6.02 x1026 (kg.mole)-1
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a) 10 A0 b) 2 A0 c) 4 A0 d) 0.25 A0

Ans: c
72. Using the following data find the type of unit cell GaAs forms:
Density of GaAs=5.324 gm/cm3 , atomic weight of GaAs is 144.6, lattice constant=5.65 A0
a) SC structure c) BCC structure
b)FCC structure d) Diamond structure

Ans: b
73. Example of Body Centered cubic structure is
a) Polonium c) Na
b) Diamond

Ans: c
74. Example of Face Centered cubic structure is
a) Copper c) Sodium
b) Diamond d) polonium

Ans: a