FIITJEE Atomic structure(DAY.

3)
BoredomCBR
1 If proton, electron and  -particle are moving with same kinetic energy then the order of their
de-Broglie’s wavelength
(A) p   e    (B)    p   e (C)     p   e (D)  e = p   
C
2 If wavelength is equal to the distance travelled by the electron in one second, then
h h h h
(A)  = (B)  = (C)  = (D)  =
p m p m
D
3 Light of wavelength  strikes a metal surface with intensity X and the metal emits Y electrons
per second of average energy Z. What will happen to Y and Z if X is halved ?
(A) Y will be halved and Z will be doubled (B) Y will be doubled and Z will be halved
(C) Y will be halved and Z will remain the same (D) Y will remain the same and Z will be
halved
C
4 The number of de-Broglie waves made by an electron in one second in the third Bohr orbit
of H-atom.
(A) 7  1024 (B) 2  1010 (C) 2  107 (D) 7  1014
D
5. The size of a micoscopic particle is one micron and mass is 6.625 x 10 –13 gram, if its
position may be measured to with is 0.1% of its size, the uncertainity in velocity in cm/sec,
is approximately
(A) 10−6 / 3 (B) 10−7 / 2 (C) 10−5 / 4 (D) 10−7 / 4
D
6 Suppose a photon of frequency (  ) causes photo electric emission from a surface with
threshold frequency ( 0 ) . What is the de-broglie wavelength of the photo electron of
maximum kinetic energy in terms of  =  − 0 ?
h h 1 1  mc 2  h 
C (A) v = (B) v = (C)  − = (D)  =  
zm    0   h  2 
7. If uncertainity in position and momentum are equal then uncertainity in velocity is
h h 1 h 1 h
(A) (B) (C) (D)
 2 2m  m 2
C
1
8. The correct designation of an electron with n = 4, = 3, m = 2 and S = is
2
(A) 3d (B) 4f (C) 5p (D) 6s

B
Comprehension – 2
The substance which contain species with unpaired electrons in their orbitals behave as
paramagnetic substances the paramagnetism is expressed in terms of magnetic moment
s = n (n + 2)BM n = no. of unpaired electrons.

If magnetic moment is zero the substance is diamagnetic

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 FIITJEE Atomic structure(DAY.3)
sees CBR
do
9 Which of the following has highest magnetic moment
(A) Ti+3 (B) Mn+2 (C) Cr +3 (D) V +3

B
10 If an ion of Mn has a magnetic moment of 3.873 BM then Mn is in which state
(A) + 2 (B) +3 (C) +4 (D) +5
C
11 Which of the following is a paramagnetic substance
(A) Mg+2 (B) Cu+ (C) Ti+2 (D) Zn+2
C
Integer Type
12 The magnetic moment of an oxide of chromium is 15B.M.
The number of electrons with Azimethal quantum number ( = 1) present in one molecule of

its oxide is 7x. What is the value of x.

(Assume that oxide is ionic compound)
6
13 A 3d electron having S = +1/2 can have magnetic quantum no
(A) +2 (B) +3 (C) –3 (D) 4
A
14 An electron has principal quantum number 3. The number of its (i) sub-shells and (ii) orbitals
would be respectively.
(A) 3 and 5 (B) 3 and 7 (C) 3 and 9 (D) 2 and 5
C
15. Which of the following sets of quantum numbers is not allowed?
(A) n = 2, l = 0, m = + 1 (B) n = 2, l = 1, m = + 1
(C) n = 2, l = 0, m = 0 (D) n = 2, l = 1, m = – 1
A
16 The orbital angular momentum of an electron in 2s orbital is
1 h h h
B (A) + (B) Zero (C) (D) 2
2 2 2 2

17. Which of the following represent(s) the correct set of four quantum numbers of a 4d electron?
B (A) 4, 3, 2, +1/2 (B) 4, 2, 1, +1/2 (C) 4, 1, –2, +1/2 (D) 4, 4, 1, –1/2

18 The electrons of the same orbital can be distinguished by

(A) Principal quantum number (B) Azimuthal quantum number
(C) Spin quantum number (D)Magnetic quantum number
C
19. Which set of quantum numbers represents the electron of lowest energy
(A) n = 2,  = 0, m = 0, S = +1/2 (B) n = 2,  = 1, m = 0, S = +1/2
(C) n = 4,  = 0, m = 0, S = +1/2 (D) n = 4,  = 0, m = 0, S = –1/2
A
20. The correct set of quantum numbers for the unpaired electron of chlorine atom is
(A) n = 2,  = 1, m = 0 (B) n = 2,  = 1, m = 1 (C) n = 3,  = 1,
m=0 (D) n = 3,  = 0, m = 0
C

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 FIITJEE Atomic structure(DAY.3)
same CBR
as
21 The orientation of an orbital in an atom is governed by the
(A) principle quantum number (B) azimuthal quantum number
(C) magnetic quantum number (D) spin quantum number
C
22. An orbital with l = 0 is
(A) symmetrical about the nucleus (B) symmetrical about the X–axis only
(C) symmetrical about the Y–axis only (D) symmetrical about the Z–axis only
A
23. In a set of degenerate orbitals, the electrons distribute themselves to retain like spins as far
as possible. This statement belongs to
(A) Pauli’s exclusive principle (B) Auf–bau principle
(C) Hund’s rule of maximum multiplicity (D) Slater rule
C
24. What are the values of the orbital angular momentum of an electron in the orbitals 1s, 3s, 3d
and 2p ?
(A) 0, 0, 6h , 2h (B) 1, 1, 4h, 2h (C) 0, 1, 6h, 3h (D) 0,0, 20h, 6h
A
25. If the quantum numbers for the 5 th electron in carbon atoms are 2, 1, 1, +1/2, then for the 6 th
electron, these values would be
(A) 2, 1, 0, –1/2 (B) 2, 0, 1, 1/2 (C) 2, 1, 1, –1/2 (D) 2, 1, –1, + ,1/2
D
26. The number of unpaired electrons in Cr3+ is
(A) 1 (B) 3 (C) 4 (D) 6
B
27. The quantum number(s) needed to describe an electron fully in an atom is/are
(A) 1 (B) 2 (C) 3 (D) 4

C
28. Which of the following sets of quantum numbers is correct for an electron in 4f orbital
a) n = 3, l = 2, m = - 2, s = +½ b) n = 4, l = 4, m = - 4, s = -½
c) n = 4, l = 3 , m = +1, s = + ½ d) n = 4, l = 3, m = +4, s = + ½

C
29. Which of the following ions has the maximum magnetic moment?
a) Mn+2 b) Fe+2 c) Ti+2 d) Cr+2
A
30. Uncertainty in position of a particle of 25 grams in space is 10 -5 m. Hence uncertainty in
velocity (m/sec) is (h = 6.6 x 10 -34 J-sec)
a) 2.1 x 10-28 b) 2.1 x 10-34 c) 0.5 x 10-34 d) 5.0 10-24
A
31. Which of the following is not possible?
a) n = 3, l = 0, m = 0b) n = 3, l = 1, m = -1
c) n = 2, l = 0, m = -1 d) n = 2, l = 1, m = 0
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 FIITJEE soooo
Atomic structure(DAY.3) CBR
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C
32. The electrons identified by quantum number n and l, (i) n = 4, l = 1 (ii) n = 4, l = 0
(iii) n = 3, l = 2 (iv) n = 3, l = 1 can be placed in order of increasing energy, from the lowest
to highest, as
a) iv < ii < iii < i b) ii < iv < i < iii c) i < iii < ii < iv d) iii < i < iv < ii
A
33 Uncertainty in position of a minute particle of mass 25g in space is 10 -5m. What is the
uncertainty in its velocity (in ms-1) ? (h = 6.6 x 10-34 Js)
1) 2.1 x 10-34 2) 0.5 x 10-34 3) 2.1 x 10-28 4) 0.5 x 10-23
3
34. Which of the following ions has the maximum magnetic moment?
1) Mn+2 2) Fe+2 3) Ti+2 4) Cr+2
1
35. The de Broglie wavelength of a tennis ball of mass 60 g moving with a velocity of 10 metres
per second is approximately
1) 10-33 metres 2) 10-31 metres 3) 10-16 metres 4) 10-25 metres
1
h
36. The orbital angular momentum for an electron revolving in an orbit is given by l (l + 1)  .
2
This momentum for an s-electron will be given by
1 h h h
1) +  2) zero 3) 4) 2
2 2 2 2
2
37. The number of d-electrons retained in Fe2+ (At. No. of Fe = 26) ion is
1) 3 2) 4 3) 5 4) 6

4
38. If the radius of first Bohr orbit of H-atom is x, then de Broglie wavelength of electron in 4 th orbit
is nearly
1) 8px 2) 6px 3) 2px 4) 9x
1
39. The wavelength associated with a golf ball weighing 100g and moving at a speed of 5m/h is
the order of
1) 10-10 m 2) 10-20 m 3) 10-30 m 4) 10-40 m
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 FIITJEE Atomic structure(DAY.3)
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3
40. What is the wave length of an electron accelerated through a potential difference of 100V?
a) 3.88 A0 b) 5.23 A0 c) 1.22 A0 d) 4.10 A0
C
41. Match the following
Column – I Column – II
A) number of values of l for an energy level P) 0, 1, 2 …. n – 1
B) actual values of l for an energy level Q) + l, ……..1,
0, ….. -1…….-l,
C) number of m1 values for a particular type of orbital R) 2l + 1
D) actual value of m1 for a particular type of orbital S) n
A–S;B–P;C–R;D–Q

42 The orbital angular momentum of differentiating electron in titanium is (Ti = 22)

h h 2h h
a) 2 b) c) d) 6
2 2 2 2
D
43. The magnetic moment of Ni+2 is (Ni = 28)
a) 2.82 BM b) 3.87 BMc) 1.73 BM d) zero
A
44 If wavelength of photon is 2.2 x 10 -11 m. Then momentum of photon is
a) 3.3 x 10-22 kg/sec b) 3 x 10-23 kg/sec c) 6.89 x 10-43 kg/sec d) 1.45 x 10-44 kg/sec
B
45. The maximum no. of electrons present in n = 5 energy level is
a) 32 b) 56 c) 18 d) 50
D
46. For an electron to have the same de Broglie wave length as that of a proton, its velocity should
be ________ times that of proton
a) 1836 b) 1/1836 c) 3672 d) 1/3672
A
47. The voltage with which an electron has to be accelerated so as to have its wavelength equal
to 1A0 is
a) 10 V b) 15 V c) 150 V d) 1 V
C

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 FIITJEE Atomic structure(DAY.3)
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CBR
48 What will be the uncertainty in velocity of an electron in order to be located within 0.005 nm?
a) 1.16 x 106 m/sec b) 1.16 x 105 m/sec c) 1.16 x 104 m/sec d) 1.16 x 107m/sec
D
 h 
49 If z – component of orbital angular momentum is +2   , then the magnitude of orbital
 2 
angular momentum can never be
h h h h
a) 2 b) 3 c) 6 d) 2 3
2 2 2 2
A,B
50
How many waves are made by a Bohr electron in one complete revolution in its third orbit?
3

PARAGRAPH:
When a particle as an electron exist in a box, three quantum numbers are necessary to describe the
spatial distribution of electrons in atoms. To describe an electron in an atom completely, a fourth
quantum number, ma, called the spin quantum number must be specified. This is because every
electron has magnetic moment associated with it, which is quantized in one of two possible
orientations. Electrons having the same spin strongly repel each other and tend to occupy different
region of space. The result of a fundamental law of nature is known as “Paul exclusion principle”.
1 1
51. The quantum numbers + and − for the electron spin represent
2 2
(A) rotation of the electron in clockwise and anticlockwise direction respectively
(B) rotation of the electron in anticlockwise and clockwise direction respectively
(C) magnetic moment of the electron pointing up and down respectively
(D) two quantum mechanical spin states which have no classical analogues.
D
52. The valence shell electron of sodium has the quantum numbers (n, ,m,s)
1 1 1 1
(A) 2,1, −1, − (B) 3,0,0, + (C) 3,2, −2, − (D) 3,2, −2, +
2 2 2 2
B

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