I PUC – NEET / JEE CHEMISTRY TOPIC: Structure of Atom By-YR

1. The number of protons, neutrons and electrons in 175Lu71, respectively, are

(a) 71, 104 and 71 (b) 104, 71 and 71
(c) 71, 71 and 104 (d) 175, 104 and 71 (NEET 2020)
2. Be2+ is isoelectronic with which of the following ions?
(a) H+ (b) Li+ (c) Na+ (d) Mg2+ (2014)
3. Isoelectronic species are
(a) CO, CN–, NO+, C22– (b) CO–, CN, NO, C2–
(c) CO+, CN+, NO–, C2 (d) CO, CN, NO, C2 (2000)
4. The ion that is isoelectronic with CO is
(a) CN– (b) N2+ (c) O2– (d) N2– (1997)
5. Which one of the following is not isoelectronic with O ? 2–

(a) Ti+ (b) Na+ (c) N3– (d) F– (1994)

6. Which of the following series of transitions in the spectrum of hydrogen atom falls in visible
region?
(a) Brackett series (b) Lyman series
(c) Balmer series (d) Paschen series (NEET 2019)
7. Calculate the energy in joule corresponding to light of wavelength 45 nm. (Planck’s
constant, h = 6.63 × 10–34 J s, speed of light, c = 3 × 108 m s–1)
(a) 6.67 × 1015 (b) 6.67 × 1011
(c) 4.42 × 10–15 (d) 4.42 × 10–18 (2014)
8. The value of Planck’s constant is 6.63 × 10 –34
Js. The speed of light is 3 × 1017 nm s–1.
Which value is closest to the wavelength in nanometer of a quantum of light with frequency
of 6 × 1015 s–1?
(a) 50 (b) 75 (c) 10 (d) 25 (NEET 2013)
9. According to law of photochemical equivalence the energy absorbed (in ergs/mole) is given
as (h = 6.62 × 10–27 ergs, c = 3 × 1010 cm s–1,
NA = 6.02 × 1023 mol–1)
(a) 1.196 ×108/ʎ (b) 2.859 105 / ʎ
(c) 2.859 ×1016 / ʎ (d) 1.196 ×1016/ ʎ (Karnataka NEET 2013)
10. The energies E1 and E2 of two radiations are 25 eV and 50 eV respectively. The relation
between their wavelengths i.e., l1 and l2 will be
(a) ʎ1 = ʎ 2 (b) ʎ1 = 2 ʎ2 (c) ʎ1 = 4 ʎ2 (d) ʎ1= ½ ʎ2 (2011)
11. The value of Planck’s constant is 6.63 × 10 –34
J s. The velocity of light is 3.0×108 ms–1.
Which value is closest to the wavelength in nanometers of a quantum of light with frequency
of 8 × 1015 s–1 ?
(a) 2 × 10–25 (b) 5 × 10–18 (c) 4 × 101 (d) 3 × 107 (2003)
12. For given energy, E = 3.03 × 10 –19
joules corresponding wavelength is
(h = 6.626 × 10 –34
J sec, c = 3 × 10 m/sec)
8

(a) 65.6 nm (b) 6.56 nm (c) 3.4 nm (d) 656 nm (2000)

13. What will be the longest wavelength line in Balmer series of spectrum?
(a) 546 nm (b) 656 nm (c) 566 nm (d) 556 nm (1996)
 𝑍2
14. Based on equation E = – 2.178 × 10–18 J , certain conclusions are written. Which of
𝑛2
them is not correct?
(a) Equation can be used to calculate the change in energy when the electron changes
orbit.
(b) For n = 1, the electron has a more negative energy than it does for n = 6 which
means that the electron is more loosely bound in the smallest allowed orbit.
(c) The negative sign in equation simply means that the energy of electron bound to
the nucleus is lower than it would be if the electrons were at the infinite distance from
the nucleus.
(d) Larger the value of n, the larger is the orbit radius. (NEET 2013)
15. According to the Bohr theory, which of the following transitions in the hydrogen atom will
give rise to the least energetic photon?
(a) n = 6 to n = 1 (b) n = 5 to n = 4
(c) n = 6 to n = 5 (d) n = 5 to n = 3 (Mains 2011)
16. The energy of second Bohr orbit of the hydrogen atom is –328 kJ mol–1; hence the energy
of fourth Bohr orbit would be
(a) – 41 kJ mol–1 (b) –82 kJ mol–1
(c) –164 kJ mol–1 (d) –1312 kJ mol–1 (2005)
17. The frequency of radiation emitted when the electron falls from n = 4 to n = 1 in a
hydrogen atom will be (Given ionization energy of H = 2.18 × 10–18 J atom–1
and h = 6.626 × 10–34 J s)
(a) 1.54 × 1015 s–1 (b) 1.03 × 1015 s–1
(c) 3.08 × 1015 s–1 (d) 2.00 × 1015 s–1 (2004)
18. In hydrogen atom, energy of first excited state is –3.4 eV. Then find out K.E. of same
orbit of hydrogen atom.
(a) +3.4 eV (b) +6.8 Ev (c) –13.6 eV (d) +13.6 eV (2002)
19. Who modified Bohr’s theory by introducing elliptical orbits for electron path?
(a) Rutherford (b) Thomson
(c) Hund (d) Sommerfeld (1999)
20. The Bohr orbit radius for the hydrogen atom (n = 1) is approximately 0.530 Å. The radius
for the first excited state (n = 2) orbit is (in Å)
(a) 4.77 (b) 1.06 (c) 0.13 (d) 2.12 (1998)
21. In a Bohr’s model of an atom, when an electron jumps from n = 1 to n = 3, how much
energy will be emitted or absorbed?
(a) 2.389 × 10–12 ergs (b) 0.239 × 10–10 ergs
(c) 2.15 × 10–11 ergs (d) 0.1936 × 10–10 ergs (1996)
22. The radius of hydrogen atom in the ground state is 0.53 Å. The radius of Li2+ ion (atomic
number = 3) in a similar state is
(a) 0.53 Å (b) 1.06 Å (c) 0.17 Å (d) 0.265 Å (1995)
23. The energy of an electron in the nth Bohr orbit of hydrogen atom is (1992)

24. The spectrum of He is expected to be similar to that

(a) H (b) Li+ (c) Na (d) He+ (1988)
25. If r is the radius of the first orbit, the radius of nth orbit of H-atom is given by
(a) rn2 (b) rn (c) r/n (d) r2n2 (1988)
26. In hydrogen atom, the de Broglie wavelength of an electron in the second Bohr orbit is
[Given that Bohr radius, a0 = 52.9 pm] (Odisha NEET 2019)
(a) 211.6 pm (b) 211.6 𝜋 pm (c) 52.9 𝜋 pm (d) 105.8 pm
27. A 0.66 kg ball is moving with a speed of 100 m/s. The associated wavelength will be
(h = 6.6 × 10–34 J s)
(a) 6.6 × 10–32 m (b) 6.6 × 10–34 m
(c) 1.0 × 10–35 m (d) 1.0 × 10–32 m (Mains 2010)
28. If uncertainty in position and momentum are equal, then uncertainty in velocity is

(2008)
29. The measurement of the electron position is associated with an uncertainty in
momentum, which is equal to 1 × 10–18 g cm s–1. The uncertainty in electron velocity is (mass
of an electron is 9 × 10–28 g)
(a) 1 × 105 cm s–1 (b) 1 × 1011 cm s–1
(c) 1 × 10 cm s
9 –1
(d) 1 × 106 cm s–1 (2008)
30. Given : The mass of electron is 9.11 × 10 –31
kg, Planck constant is 6.626 × 10–34 J s, the
uncertainty involved in the measurement of velocity within a distance of 0.1 Å is
(a) 5.79 × 105 m s–1 (b) 5.79 × 106 m s–1
(c) 5.79 × 107 m s–1 (d) 5.79 × 108 m s–1 (2006)
31. The uncertainty in momentum of an electron is 1 × 10–5 kg m/s. The uncertainty in its
position will be (h = 6.62 × 10–34 kg m2/s)
(a) 5.27 × 10–30 m (b) 1.05 × 10–26 m
(c) 1.05 × 10 –28
m (d) 5.25 × 10–28 m (1999)
32. The de Broglie wavelength of a particle with mass 1 g and velocity 100 m/s is
(a) 6.63 × 10–35 m (b) 6.63 × 10–34 m
(c) 6.63 × 10 –33
m (d) 6.65 × 10–35 m (1999)
33. The position of both, an electron and a helium atom is known within 1.0 nm. Further the
momentum of the electron is known within 5.0 × 10–26 kg m s–1. The minimum uncertainty in
the measurement of the momentum of the helium atom is
(a) 8.0 × 10–26 kg m s–1 (b) 80 kg m s–1
(c) 50 kg m s–1 (d) 5.0 × 10–26 kg m s–1 (1998)
34. Uncertainty in position of an electron (Mass = 9.1 × 10–28 g) moving with a velocity of
3 × 104 cm/s accurate upto 0.001% will be (Use h/(4𝜋) in uncertainty expression where
h = 6.626 × 10–27 erg second)
(a) 5.76 cm (b) 7.68 cm (c) 1.93 cm (d) 3.84 cm (1995)
35. Which of the following statements do not form a part of Bohr’s model of hydrogen atom?
(a) Energy of the electrons in the orbits are quantized.
(b) The electron in the orbit nearest the nucleus has the lowest energy.
(c) Electrons revolve in different orbits around the nucleus.
(d) The position and velocity of the electrons in the orbit cannot be determined
simultaneously. (1989)
36. 4d, 5p, 5f and 6p orbitals are arranged in the order of decreasing energy. The correct
option is
(a) 5f > 6p > 4d > 5p (b) 5f > 6p > 5p > 4d
(c) 6p > 5f > 5p > 4d (d) 6p > 5f > 4d > 5p (NEET 2019)
37. Orbital having 3 angular nodes and 3 total nodes is
(a) 5p (b) 3d (c) 4f (d) 6d (Odisha NEET 2019)
38. Which one is a wrong statement?
(a) Total orbital angular momentum of electron in s-orbital is equal to zero.
(b) An orbital is designated by three quantum numbers while an electron in an atom is
designated by four quantum numbers.

(c) The electronic configuration of N atom is

(d) The value of m for dz2 is zero. (NEET 2018)
39. Which one is the wrong statement?

(a) The uncertainty principle is

(b) Half filled and fully filled orbitals have greater stability due to greater exchange
energy, greater symmetry and more balanced arrangement.
(c) The energy of 2s-orbital is less than the energy of 2p-orbital in case of hydrogen
like atoms.

(d) de-Broglie’s wavelength is given by

where m = mass of the particle, v = group velocity of the particle. (NEET 2017)
40. How many electrons can fit in the orbital for which n = 3 and l = 1?
(a) 2 (b) 6 (c) 10 (d) 14 (NEET-II 2016)
41. Which of the following pairs of d-orbitals will have electron density along the axes?
(a) dz2, dxz (b) dxz, dyz
(c) dz , dx – y
2 2 2
(d) dxy, dx2 – y2 (NEET-II 2016)
42. Two electrons occupying the same orbital are distinguished by
(a) azimuthal quantum number (b) spin quantum number
(c) principal quantum number (d) magnetic quantum number.(NEET-I 2016)
43. Which is the correct order of increasing energy of the listed orbitals in the atom of
titanium? (At. no. Z = 22)
(a) 4s 3s 3p 3d (b) 3s 3p 3d 4s
(c) 3s 3p 4s 3d (d) 3s 4s 3p 3d (2015)
44. The number of d-electrons in Fe2+ (Z = 26) is not equal to the number of electrons in
which one of the following?
(a) d-electrons in Fe (Z = 26) (b) p-electrons in Ne (Z = 10)
(c) s- electrons in Mg (Z=12) (d) p-electrons in Cl (Z = 17) (2015, Cancelled)
45. The angular momentum of electron in ‘d’ orbital is equal to

(2015, Cancelled)
46. What is the maximum number of orbitals that can be identified with the following
quantum numbers? n = 3, l = 1, ml = 0
(a) 1 (b) 2 (c) 3 (d) 4 (2014)
47. What is the maximum numbers of electrons that can be associated with the following set
of quantum numbers? n = 3, l = 1 and m = -1
(a) 4 (b) 2 (c) 10 (d) 6 (NEET 2013)
48. The outer electronic configuration of Gd (At. No. 64) is
(a) 4f55d46s1 (b) 4f75d16s2
(c) 4f35d56s2 (d) 4f45d56s1 (Karnataka NEET 2013)
49. Maximum number of electrons in a subshell with l = 3 and n = 4 is
(a) 14 (b) 16 (c) 10 (d) 12 (2012)
50. The correct set of four quantum numbers for the valence electron of rubidium atom
(Z = 37) is
(a) 5, 1, 1, +1/2 (b) 6, 0, 0, +1/2
(c) 5, 0, 0, +1/2 (d) 5, 1, 0, +1/2 (2012)
51. The orbital angular momentum of a p-electron is given as

(Mains 2012)
52. The total number of atomic orbitals in fourth energy level of an atom is
(a) 8 (b) 16 (c) 32 (d) 4 (2011)
53. If n = 6, the correct sequence for filling of electrons will be
(a) ns -- (n - 2)f -- (n -1)d -- np
(b) ns -- (n - 1)d -- (n -2)f -- np
(c) ns -- (n - 2)f -- np -- (n -1)d
(d) ns -- np -- (n -1)d --(n - 2)f (2011)
54. Maximum number of electrons in a subshell of an atom is determined by the following
(a) 2l + 1 (b) 4l - 2 (c) 2n2 (d) 4l + 2 (2009)
55. Which of the following is not permissible arrangement of electrons in an atom?
(a) n = 5, l = 3, m = 0, s = +1/2 (b) n = 3, l = 2, m = -3, s = -1/2
(c) n = 3, l = 2, m = -2, s = -1/2 (d) n = 4, l = 0, m = 0, s = -1/2 (2009)
56. Consider the following sets of quantum numbers:
n l m s
i 3 0 0 +1/2
ii 2 2 1 +1/2
iii 4 3 -2 -1/2
iv 1 0 -1 -1/2
v 3 2 3 +1/2
Which of the following sets of quantum number is not possible?
(a) (i), (ii), (iii) and (iv) (b) (ii), (iv) and (v)
(c) (i) and (iii) (d) (ii), (iii) and (iv) (2007)
57. The orientation of an atomic orbital is governed by
(a) principal quantum number (b) azimuthal quantum number
(c) spin quantum number (d) magnetic quantum number. (2006)
58. The following quantum numbers are possible for how many orbitals?
n = 3, l = 2, m = +2
(a) 1 (b) 2 (c) 3 (d) 4 (2001)
59. For which of the following sets of four quantum numbers, an electron will have the
highest energy?
n l m s
a 3 2 1 +1/2
b 4 2 -1 +1/2
c 4 1 0 -1/2
d 5 0 0 -1/2
(1994)
60. Electronic configuration of calcium atom can be written as
(a) [Ne]4p2 (b) [Ar]4s2
(c) [Ne]4s2 (d) [Kr]4p2 (1992)
61. In a given atom no two electrons can have the same values for all the four quantum
numbers. This is called
(a) Hund’s Rule (b) Aufbau principle
(c) Uncertainty principle (d) Pauli’s Exclusion principle. (1991)
62. For azimuthal quantum number l = 3, the maximum number of electrons will be
(a) 2 (b) 6 (c) 0 (d) 14 (1991)
63. The order of filling of electrons in the orbitals of an atom will be
(a) 3d, 4s, 4p, 4d, 5s (b) 4s, 3d, 4p, 5s, 4d
(c) 5s, 4p, 3d, 4d, 5s (d) 3d, 4p, 4s, 4d, 5s (1991)
64. The electronic configuration of Cu (atomic number 29) is
(a) 1s2 2s2 2p6 3s23p6 4s23d9
(b) 1s2 2s2 2p6 3s2 3p63d10 4s1
(c) 1s2 2s22p6 3s23p6 4s24p6 5s25p1
(d) 1s2 2s22p6 3s23p6 4s24p63d3 (1991)
65. The total number of electrons that can be accommodated in all the orbitals having
principal quantum number 2 and azimuthal quantum number 1 are
(a) 2 (b) 4 (c) 6 (d) 8 (1990)
66. An ion has 18 electrons in the outermost shell, it is
(a) Cu+ (b) Th4+ (c) Cs+ (d) K+ (1990)
67. Number of unpaired electrons in N is/are
2+

(a) 2 (b) 0 (c) 1 (d) 3 (1989)

68. The maximum number of electrons in a subshell is given by the expression
(a) 4l -2 (b) 4 l + 2 (c) 2 l + 2 (d) 2n2 (1989)
69. The number of spherical nodes in 3p orbitals are/is
(a) one (b) three (c) none (d) two (1988)
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