Chapter 2

Structure of Atom
1. Calculate the wavelength (in nanometer) associated (c) n = 3, l = 2 (d) n = 3, l = 1
with a proton moving at 1.0 × 103 ms–1
can be placed in order of increasing energy as
(Mass of proton = 1.67 × 10–27 kg and h = 6.63 × [AIEEE-2012]
10–34 Js) [AIEEE-2009] (1) (d) < (b) < (c) < (a)
(1) 0.40 nm (2) 2.5 nm (2) (b) < (d) < (a) < (c)
(3) 14.0 nm (4) 0.032 nm
(3) (a) < (c) < (b) < (d)
2. In an atom, an electron is moving with a speed of (4) (c) < (d) < (b) < (a)
600 m/s with an accuracy of 0.005%. Certainity with
which the position of the electron can be located is 7. Energy of an electron is given by
(h = 6.6 × 10–34 kg m2s–1, mass of electron, em = 9.1
⎛ Z2 ⎞
× 10–31 kg) [AIEEE-2009] E  2.178 1018 J⎜⎜ 2 ⎟⎟. Wavelength of light
(1) 5.10 × 10–3 m (2) 1.92 × 10–3 m ⎝n ⎠
required to excite an electron in an hydrogen atom
(3) 3.84 × 10–3 m (4) 1.52 × 10–4 m
form level n = 1 to n = 2 will be
3. The energy required to break one mole of Cl – Cl
(h = 6.62 × 10–34 Js and c = 3.0 × 108 ms–1)
bonds in Cl 2 is 242 kJ mol –1 . The longest
[JEE (Main)-2013]
wavelength of light capable of breaking a single
Cl – Cl bond is (1) 1.214 × 10–7 m (2) 2.816 × 10–7 m
(c = 3 × 108 ms–1 and NA = 6.02 × 1023 mol–1) (3) 6.500 × 10–7 m (4) 8.500 × 10–7 m
[AIEEE-2010] 8. The first ionisation potential of Na is 5.1 eV. The
(1) 494 nm (2) 594 nm value of electron gain enthalpy of Na+ will be
[JEE (Main)-2013]
(3) 640 nm (4) 700 nm
(1) –2.55 eV (2) –5.1 eV
4. Ionisation energy of He+ is 19.6 × 10–18 atom–1.
The energy of the first stationary state (n = 1) of (3) –10.2 eV (4) +2.55 eV
Li2+ is [AIEEE-2010] 9. The correct set of four quantum numbers for the
(1) 8.82 × 10–17 J atom–1 valence electrons of rubidium atom (Z = 37) is
[JEE (Main)-2014]
(2) 4.41 × 10–16 J atom–1
(3) –4.41 × 10–17 J atom–1 1 1
(1) 5, 0, 0,  (2) 5,1, 0, 
(4) –2.2 × 10–15 J atom–1 2 2

5. The frequency of light emitted for the transition 1 1

n = 4 to n = 2 of He + is equal to the transition in (3) 5,1,1,  (4) 5, 0,1, 
2 2
H atom corresponding to which of the following
[AIEEE-2011] 10. Which of the following is the energy of a possible
excited state of hydrogen? [JEE (Main)-2015]
(1) n = 4 to n = 3 (2) n = 3 to n = 1
(1) +13.6 eV
(3) n = 2 to n = 1 (4) n = 3 to n = 2
(2) –6.8 eV
6. The electrons identified by quantum numbers n
and l (3) –3.4 eV
(a) n = 4, l = 1 (b) n = 4, l = 0 (4) +6.8 eV

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11. A stream of electrons from a heated filament was (c) According to wave mechanics, the ground
passed between two charged plates kept at a h
potential difference V esu. If e and m are charge state angular momentum is equal to
2
and mass of an electron, respectively, then the
(d) The plot of  Vs r for various azimuthul
h quantum numbers, shows peak shifting
value of (where  is wavelength associated with
 towards higher r value. [JEE (Main)-2019]
electron wave) is given by [JEE (Main)-2016]
(1) (a), (d) (2) (b), (c)
(1) 2meV
(3) (a), (c) (4) (a), (b)
(2) meV
16. Which of the graphs shown below does not
(3) 2meV represent the relationship between incident light and
(4) meV the electron ejected from metal surface?
12. The radius of the second Bohr orbit for hydrogen [JEE (Main)-2019]
atom is
(Planck's Const. h = 6.6262 × 10–34 Js;
K.E.
mass of electron = 9.1091 × 10–31 kg; of e s

charge of electron e = 1.60210 × 10–19 C;

(1)
permittivity of vacuum
0 Energy of
0 = 8.854185 × 10–12 kg–1 m–3 A2)
Light
[JEE (Main)-2017]
(1) 0.529 Å (2) 2.12 Å
(3) 1.65 Å (4) 4.76 Å Number
of e s
13. The highest value of the calculated spin only
magnetic moment (in BM) among all the transition
metal complexes is [JEE (Main)-2019] (2)

(1) 5.92 (2) 6.93 0 Frequency of

Light
(3) 4.90 (4) 3.87
14. For emission line of atomic hydrogen from ni = 8
 K.E.
to nf = n, the plot of wave number (  ) against
of e s
⎛ 1⎞
⎜⎝ 2 ⎟⎠ will be (The Rydberg constant, RH is in wave
n (3)
number unit) [JEE (Main)-2019]
0 Intensity of
(1) Linear with slope RH LIght
(2) Linear with intercept –RH
(3) Non-linear
K.E.
(4) Linear with slope –RH of e s

15. Which of the following combination of statements

is true regarding the interpretation of the atomic (4)
orbitals? 0 Frequency of
(a) An electron in an orbital of high angular Light
momentum stays away from the nucleus than
17. The ground state energy of hydrogen atom is
an electron in the orbital of lower angular
–13.6 eV. The energy of second excited state of
momentum
He+ ion in eV is [JEE (Main)-2019]
(b) For a given value of the principal quantum
(1) –27.2 (2) –6.04
number, the size of the orbit is inversely
proportional to the azimuthal quantum number. (3) –54.4 (4) –3.4
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18. Heat treatment of muscular pain involves radiation of The correct order of their increasing energies will
wavelength of about 900 nm. Which spectral line of be [JEE (Main)-2019]
H-atom is suitable for this purpose? (1) IV < II < III < I (2) I < III < II < IV
[RH= 1 × 105 cm, h = 6.6 × 10–34 Js, c = 3 × 108 ms–1] (3) IV < III < II < I (4) I < II < III < IV
[JEE (Main)-2019]
23. If p is the momentum of the fastest electron
(1) Balmer,  2 (2) Lyman,  1 ejected from a metal surface after the irradiation of
(3) Paschen, 5  3 (4) Paschen,  3 light having wavelength , then for 1.5 p momentum
of the photoelectron, the wavelength of the light
19. The de Broglie wavelength () associated with a should be
photoelectron varies with the frequency () of the
incident radiation as, [0 is threshold frequency] (Assume kinetic energy of ejected photoelectron to be
very high in comparison to work function):
[JEE (Main)-2019]
[JEE (Main)-2019]
1 1
(1)   (2)   3 4
   0     0  4
1
(1)  (2) 
4 9

1 1 2 1
(3)   1
(4)   3 (3)  (4) 
3 2
 
 0 2   0 2 
24. For any given series of spectral lines of atomic
20. What is the work function of the metal if the light
hydrogen, let   max  min be the difference in
of wavelength 4000 Å generates photoelectrons of
velocity 6 × 105 ms–1 from it? maximum and minimum frequencies in cm–1. The

(Mass of electron = 9 × 10–31 kg ratio Lyman / Balmer is [JEE (Main)-2019]

Velocity of light = 3 × 108 ms–1 (1) 9 : 4 (2) 27 : 5
Planck’s constant = 6.626 × 10–34 Js (3) 4 : 1 (4) 5 : 4
Charge of electron = 1.6 × 10–19 JeV–1) 25. Which one of the following about an electron
[JEE (Main)-2019] occupying the 1s orbital in a hydrogen atom is
incorrect? (The Bohr radius is represented by a0)
(1) 4.0 eV (2) 2.1 eV
[JEE (Main)-2019]
(3) 3.1 eV (4) 0.9 eV
(1) The probability density of finding the electron is
21. If the de Broglie wavelength of the electron in nth maximum at the nucleus
Bohr orbit in a hydrogenic atom is equal to 1.5 a0
(a0 is Bohr radius), then the value of n/z is (2) The electron can be found at a distance 2a0
from the nucleus
[JEE (Main)-2019]
(3) The magnitude of the potential energy is double
(1) 0.40 (2) 1.50 that of its kinetic energy on an average
(3) 0.75 (4) 1.0 (4) The total energy of the electron is maximum
22. The quantum number of four electrons are given when it is at a distance a0 from the nucleus
below 26. The graph between ||2 and r(radial distance) is
1 shown below. This represents [JEE (Main)-2019]
(I) n = 4, l = 2, ml = –2, ms = 
2
1
(II) n = 3, l = 2, ml = 1, ms =  ||2
2
1
(III) n = 4, l = 1, ml = 0, ms = 
2 r

1 (1) 1s orbital (2) 2s orbital

(IV) n = 3, l = 1, ml = 1, ms = 
2 (3) 2p orbital (4) 3s orbital

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27. The ratio of the shortest wavelength of two spectral 4a0 4a0
series of hydrogen spectrum is found to be about (1) (2)
3 9
9. The spectral series are [JEE (Main)-2019] 2a0 2a0
(3) (4)
(1) Paschen and Pfund (2) Brackett and Pfund 3 9
(3) Lyman and Paschen (4) Balmer and Brackett 33. The de Broglie wavelength of an electron in the 4th
Bohr orbit is [JEE (Main)-2020]
28. The electrons are more likely to be found
(1) 4a0 (2) 6a0
[JEE (Main)-2019] (3) 8a0 (4) 2a0
34. The figure that is not a direct manifestation of the
a  (x) quantum nature of atoms is [JEE (Main)-2020]
 Increasing wavelength
b x
–x
(1)
c

Absorption spectrum
(1) In the region a and c (2) Only in the region c
Internal
(3) Only in the region a (4) In the region a and b energy
(2) of
29. Among the following, the energy of 2s orbital is Ar 300 400 500 600
lowest in [JEE (Main)-2019]
Temperature (K)
(1) Li (2) K
(3) H (4) Na T2 > T1
Intensity
30. The number of orbitals associated with quantum of black body
(3) radiation T1
1
numbers n = 5, ms =  is [JEE (Main)-2020]
2 Wavelength

(1) 15 (2) 50 Rb K
Na
Kinetic
(3) 25 (4) 11 energy of
(4) photoelectrons
31. For the Balmer series in the spectrum of H atom,
Frequency of incident
⎪⎧ 1 1 ⎪⎫ radiation
  RH ⎨ 2  2 ⎬ , the correct statements among (I)
⎪⎩ n1 n2 ⎪⎭ 35. The number of subshells associated with n = 4 and
m = –2 quantum numbers is [JEE (Main)-2020]
to (VI) are
(1) 2 (2) 8
(I) As wavelength decreases, the lines in the (3) 4 (4) 16
series converge
36. The region in the electromagnetic spectrum where
(II) The integer n1 is equal to 2 the Balmar series lines appear is
(III) The lines of longest wavelength corresponds to [JEE (Main)-2020]
n2 = 3 (1) Microwave (2) Ultraviolet
(IV) The ionization energy of hydrogen can be (3) Visible (4) Infrared
calculated from wave number of these lines 37. The shortest wavelength of H atom in the Lyman
series is 1. The longest wavelength in the Balmar
[JEE (Main)-2020]
series of He+ is [JEE (Main)-2020]
(1) (I), (II), (III) (2) (II), (III), (IV)
51 361
(3) (I), (III), (IV) (4) (I), (II), (IV) (1) (2)
9 5
32. The radius of the second Bohr orbit, in terms of the 271 91
Bohr radius, a0, in Li2+ is [JEE (Main)-2020] (3) (4)
5 5

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38. The correct electronic configuration and spin-only 40. The correct statement about probability density
magnetic moment (BM) of Gd 3+ (Z = 64), (except at infinite distance from nucleus) is
respectively, are [JEE (Main)-2020] [JEE (Main)-2020]
(1) [Xe] 5f7 and 8.9 (1) It can never be zero for 2s orbital
(2) [Xe] 4f7 and 7.9 (2) It can be zero for 3p orbital
(3) [Xe] 5f7 and 7.9 (3) It can be zero for 1s orbital
(4) [Xe] 4f7 and 8.9 (4) It can be negative for 2p orbital
39. The difference between radii of 3rd
and 4th
orbits of 41. The work function of sodium metal is
Li2+ is R1. The difference between the radii of 3rd 4.41 × 10–19 J. If photons of wavelength 300 nm
and 4 th orbits of He + is R 2 . Ratio are incident on the metal, the kinetic energy of the
R1 : R2 is [JEE (Main)-2020] ejected electrons will be (h = 6.63 × 10–34 J s;
(1) 3 : 2 (2) 8 : 3 c = 3 × 108 m/s) ________ × 10–21 J.
(3) 2 : 3 (4) 3 : 8 [JEE (Main)-2020]

  

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