Textbook

Chapter No.

04 Structure of Atom

Different Colours Produced in Fireworks

Subtopics
4.1 Subatomic particles
4.2 Atomic number and atomic mass number
4.3 Isotopes, isobars and isotones
4.4 Drawbacks of Rutherford atomic model
4.5 Developments leading to the Bohr's atomic
model
4.6 Bohr's model for hydrogen atom
4.7 Quantum mechanical model of atomn

Fireworks employ the principle of emission

spectrum. Each time one of the fireworks
explodes, a carefully designed mixture of
explosives, combustible fuel, and compounds
containing metals provide the desired effect.
The colours are produced by heating the metal
atoms, which then emit light in a colour
characteristic of the metal. Some common
colours and metals added to produce firework
are:

Red Colour > Lithium or strontium

Orange Colour Calcium
Yellow Colour Sodium
Green Colour > Barium
Blue Colour > Copper or lead
White Colour > Magnesium

Quick Review

Properties of subatomic particles:

Absolute Relative Symbol Approximate
Name Symbol
charge/C charge for charge Mass/kg Mass/u
mass/u

Electron e -1.6022 x 100-19 9.10938 x 10-! 0.00054

Proton +1.6022 x 109 +1 te 1.6726 x 10 1.00727
Neutron 1.67493 x 10 1.00867

8
 Chapter 04: Structure of Atom

Isotopes, isobars and isotones:

Similarities Differences Examples
Atomie spccies
Isotepes Isotopes have sanne: Isotopes have different:
atomic number (Z) mass number (A)
nunber of' protons number of neutrons
number of clectrons physical properties
clectronic configuration
position in the periodic table
chemical properties (similar) Isobars have different: 18Ar, K, Ca
Isobars Isobars have sanme:
mass number (A) atomic number (Z)
number of nucleons number of protons, electrons
and neutrons
electronic configuration
position in the periodic table
chemical properties
Isotones Isotones have same: Isotones have different: isi, P, 2s
number of neutrons Atomic number and mass K, 0Ca
number
protons and electrons
electronic configuration
position in the periodic table

Evolution of quantum theory:

Classical theory
Matter is composed of particles
and radiation has wave nature.

Einstein| Planck
Energy is Quantized.
Bohr

Line spectra (Bohr's H atom)

De Broglie
Matter wave
Heisenberg
Uncertainty principle
Schrodinger
Quantum theory
Radiation and matter both
have particle and wave nature.

Series of emission spectral ines for hydrogen:

Series n n Spectral region
Lyman 2,3.... Ultraviolet
Balmer 2 3,4,.... Visible
Paschen 3 4,5,.... Infrared
Bracket 4 5,6,.. Infrared
Pfund 6,7,.. Infrared
 MHT-CET Triumph Chemistry (Mcas)
Quantum numbers:
Quantumn numbers

Principal quantunm Azimuthal Magnetic orbital Spin quantum

number (n) (or subsidiary quantum quantum number (m) number (m,)
'n' is a positive integer number () Can have values Can have values +1/2
and has values 1, 2, 3, 4 Can have the positive between -I and +/ for clockwise spin and
and so on. values between 0 and through 0. -1/2 for anticlockwise
(n - 1).
spin.

Order of filling electrons in orbitals:

Is< 2s< 2p < 3s < 3p< 4s < 3d < 4p < 5s < 4d < Sp< 6s< 4f< 5d < 6p < 7s and so on.

Formulae 7. Energy of an electron (E,) in the n" orbit of

hydrogen-like species:
1. Number of neutrons = A -Z 72
where, E, =-2.18 x 10-18
A = mass number
}= atomic number where, Z= Atomic number

n
2. Frequency (v) =* 8. Radius of Bohr's orbit (r) = 52.9 x
Where,
v= Frequency of electromagnetic radiation 9. Energy difference for an electronic transition
c= Speed of light = 3 x 10 ms in hydrogen atom:
)=Wavelength of electromagnetic radiation AE = 2.18 x 10-l8
n,
3. Wave number (v)= n=n = lower energy level
4 n;= n = higher energy level
Energy of quantumof radiation (E)
h h
= hv = h= hcv 10. de Broglie equation: à= mv

where, h = Planck's constant = 6.626 x 10-34 J s p=mv = momentum of particle

S. Wave number of series of hydrogen
spectrum:
11. Heisenberg's uncertainty principle:
cm Ar Ap, 4

where, where,
P= wave number Ar= uncertainty in position,
RH= Rydberg constant = 109677 cm' Ap, = uncertainty in momentum
= 1.09677 x10' m
n =lower energy level Arx A(mv,) > (p=mv,)
n; = higher energy level
Ar x m x Av, 2
6. Bohr's frequency rule:
AE I, - E
V
12. Maximum number of electrons in each
where. principal shell = 2n electrons
Ej =Energy of lower energy state Maximum number of electrons in each
13.
E; = Energy of higher energy state subshell = 2(2/+ 1) electrons
10
 Chapter 04: Structure of Atom
7 Which of the following atoms contain the least
Classwork number of neutrons?
(A) (B)
4.1 Subatomic particles 9 Np
239
(C) (D)
Which of the following is an INCORRECT The charge on the atom containing 17 protons.
8
statement?
18 neutrons and 18 electrons is
(A) Mass of an electron is equal to /1837" (A) + | (B) -2 (C) -- | (D) zero
the mass of an atom ofhydrogen.
(B) The approximate mass of one proton is 9. The number of electrons in [K' is
I u. (A) 19 (B) 18 (C) 20 (D) 40
(C) When electric field of fixed strength is
applied. cathode rays are deflected 10. The introduction of a neutron into the nucleus of
towards negative electrode. an atom would lead to a change in
(D) Dalton's atomic theory was not able to (A) the number of electrons
explain why ebonite when rubbed with (B) the chemical nature of the atom
silk or fur, generates electricity. (C) the atomic number
(D) mass number
2 Neutron is a fundamental particle carrying
4.3 Isotopes, isobars and isotones
(A) aunit positive charge and having a mass
of 1.00867 amu 11. $CI and CI differ from each other in the
(B) no charge and having a mass of number of
1.00867 amu (A) electrons (B) nucleons
(C) no charge and no mass (C) protons (D) both (B) and (C)
(D) a unit negative charge and having a mass 12. Which of the following statements is TRUE?
of 1.00727 amu
(A) Isobars have similar chemical properties
3 In Rutherford's experiment, a-particles were and occupy same position in the periodic
deflected because of table.
(A) electrostatic repulsion between the (B) Isotopes have different chemical
a-particles and positively charged part of properties and occupy same position in
the atom the periodic table.
electrostatic attraction between the (C) Isotopes have different chemical
(B)
a-particles and positively charged part of properties and occupy different position
the atom in the periodic table.
(C) electrostatic repulsion between the (D) Isobars have different chemical properties
a-particles and negatively charged part of and occupy different position in the
the atom periodic table.
(D) electrostatic attraction between the 13. Kand Ca are
a-particles and empty space within the (A) isotones (B) isobars
atom
(C) isotopes (D) isomers
4. ldentify X' in the following transmutation. 14. Chlorine exists in two isotopic forms, CI-37 and
"N+ Sa ’X+ }H CI-35 but its atomic mass is 35.5 u. The ratio of
(A) "o (B) "o (C) "o (D) N CI-37 and Cl-35 is approximately
(A) I:2 (B) 1:1
4.2 Atomic number and atomicmass number (C) 1:3 (D) 3:1I
5. The number of electrons in a neutral atom of an 4.5 Developments leading to the Bohr's atomic
element is equal to its model
(A) atomic mass number
(B) atomic number 15. Which of the following could be explained by
(C) equivalent weight treating light as an electromagnetic wave?
(D) neutron number i Diffraction of light
Photoelectric effect
Which of the following is the CORRECT I. Black-body radiation
representation of a neutral atom of elenent X IV. Interference of light
having 17 protons and 18neutrons? (A) iand ii (B) ii and iv
(A) X (B) "X (C) x (D) X (C) iand iv (D) ii and iii
11
MHT-CET Triumph Chemistry (MCQs)
16. Which of the following statements is 24. In Bobr's model, the atomic radius of the first
INCORRECT about electromagnetic radiations? orbit is Y, then the atomic radius of the third
(A) Different radiations bave different orbit, is
frequencies and different wavelengths. (A) y/3 (B)
(B) All electromagnetic radiations are (C) 3y (D) 9y
composed of electrical and magnetic
25. The radius of which of the following orbit is
components.
same as that of the first Bohr's orbit of
(C) yrays have the maximum speed. hydrogen atom?
(D) The radiofrequency region is around (A) He (n=2) (B) Li (n 2)
10 Hz while ultraviolet region is around (C) Li (n =3) (D) Be" (n=2)
10 Hz.
26. Time taken for an elcctron to complete one
17. The radiation with maximum frequency is revolution in the Bohr's orbit of hydrogen atom
is
(A) Microwaves (B) IR rays nh
47'mr
(C) UV rays (D) Radiowaves (A) nh
(B) 4n'mr
18. The frequency of an electromagnetic radiation is (C)
nh
(D)
2 x 10° Hz. What is its wavelength in metres? 4n'mr 2Tmr
(Velocity of light is 3 x 10 ms)
(A) 6.0 × 10'4 1.5 x 10 27. To which electron transition between Bohr
(B) orbitals in hydrogen does the second line in the
(C) 1.5 x 10 (D) 0.66 x 102 Balmer series belong?
19. The frequency of yellow light having (A) 3’2 (B) 4-’2
wavelength 600 nm is Hz. (C) 5’2 (D) 6’ 2
(A) 5.0 x 104 (B) 5.0 x 10" 28. In Balmer series of hydrogen atom spectrum,
(C) 2.5 x 10 l4 (D) 2.5 x 10' which electronic transition causes third line?
20. The frequency of a wave of light is (A) Fifth Bohr orbit to second one.
(B) Fifth Bohr orbit to first one.
12 x 10 s .The wave number associated with
(C) Fourth Bohr orbit to second one.
this light is
(A) 5 x 10 m (B) 4 x 10- cm-l (D) Fourth Bohr orbit to first one.
(C) 2x 10- m-! (D) 4 x 10 cm 29. Which among the following transition will give
21. Select the INCORRECT statement.
Lyman series in the hydrogen line spectrum?
(A) K to L (B) L to M
(A) Quantum refers to the largest quantity of (C) L to K (D) M to L
energy that can be emitted or absorbed in
the form of electronmagnetic radiation. 30. What is the energy in joules produced when an
(B) When an excited species gives away the electron moves from n = 4 to n = 3 level in a
absorbed energy in the form of radiation, hydrogen atom?
the process is called emission of radiation. (A) -3.13 x 10-l8j (B) -2.18 x 10J
(C) When electricdischarge is passed through (C) -1.06 x10J (D) -4.36 x 10
gaseous hydrogen, it emits radiation. 31. Select the CORRECT statement.
(D) Hydrogen emission spectrum comprised
of a series of lines corresponding to (A) Bohr model was able to explain the
different frequencies. spectrum of atoms other than hydrogen.
(B) Bohr's atomic model explained the finer
4.6 Bohr's model for hydrogen atom details of the hydrogen atom spectrum.
22. Bohr's model of an atom CANNOT eXplain the
(C) Bohr's theory could explain Zeeman
effect and Stark effect.
atomicspectrumof species. (D) Bohr's theory failed to explain the ability
(A) Li2+ (B) He
of atoms to form molecules by chemical
(C) H (D) Lit bonds.

23. Calculate the energy (in joules) associated with 32. Among the following, the minimum de-Broglie
the second orbit of He". wavelength is associated with
(A) 0.545 ×10J (B) - 8.72 x 10 (A) electron (B) proton
(C) 6.2 x 10 "J (D) 2.18 x 10 8 (C) C0, molecule (D) SO, molecule

12
 Chapter 04: Structure of Atom
33. Ifwavelength of photon is 2.2 x 10m, 4.7 Quantum mechanical model of atom
h=6.6 x 1034 Js, then momentum of photon is
Atomic orbitals and quantum numbers
(A) 3 x 10 kg ms 40. The value of azimuthal quantum number () for
electrons present in 4p subshell is
(B) 3 x 10 kg m s
1.5 x 10** kg m s (A) 1 (B) 2
(C)
(C) 3 (D) 4
(D) 6.9 x 10* kg m s
41. The designation of a subshell with n = 4 and
34. Calculate the wavelength (in nm) associated |=3 is
with a proton moving at 1.0 x 10 ms, (A) 4s (B) 4p
(Mass of proton= 1.67 x 10 kg and (C) 4d (D) 4f
h=6.63 x 10* Js). 42. If the value of azimuthal quantum number of an
(A) 0.032 nm (B) 0.40 nm electron is 2, then which of the following value
(C) 2.5 nm (D) 14.0 nm of magnetic quantum numbers is NOT
permissible?
35. According to Heisenberg's uncertainty
(A) 0 (B) 2
principle, the product of uncertainties in position
and velocities for an electron of mass (C) -2 (D) 3
9.1 x 10 kg is 43. If m, has seven values, the value of azimuthal
(A) >2.8 x 10ms! quantum number should be
(B) >3.8 x 10 msl (A) 1 (B) 2
>5.8 x 10 m' sl (C) 3 (D) 4
(C)
(D) >6.8 x 10- ms! 44. For azimuthal quantum number ! = 3, the
maximum number of electrons will be
36. An atomn has a mass of 0.02 kg and uncertainty (A) 2 (B) 6
in its velocity is 9.218 x 10 m's, then (C) 0 (D) 14
uncertainty in position is
(h=6.626 x 10-34Js) 45. The maximum number of 4f electrons having
(A) 2.86 x 1028 m (B) 2.86 x 10 cm spin quantum number
(C) 1.5 x 10-27 m (D) 3.9 x10-1 m
(A) 4 (B)
37. If uncertainty in position and momentum are (C) 7 (D) 14
equal, then uncertainty in velocity is 46. Which of the following sets of quantum
(A) (B) numbers is NOT permitted?
mV
(A) n=3, /= 3, m, =0, m, =+
(C)
1h (D)
2m V (B) n= 3, 7= 2, m,= +2, m, =
38. The uncertainties in the velocities of two
particles A and B are 0.0S and 0.02 m s (C) n=3, l= 1, m, =-1, m, =-,
respectively. The mass of B is five times to that
of the mass of A. What is the ratio of (D) n=3,1=0, m, =0, m, =+
2
uncertainties Ax in their positions?
47. Which of the following sets of quantum
(A) 2 (B) 0.25 numbers is CORRECT for an electron in
4f orbital?
(C) 4 (D) 1
(A) n=4,l=3, m,=+1, m, =+
39. The measurement of the electron position is
associated with an uncertainty in momentum,
(B) n=4,7 4, m, =4, m, =
which is equal to I x 10 g cm s. The
uncertainty in electron velocity is
(mass of an electron is 9 x 10g). (C) n=4,l=3, m, =+4, m, =+
(A) 1x 10 cm s (B) I x 10 cm !
Ix 10° cm s (D) n=3,7=2, m, =-2, m, =+
(C) I x 10' cm s (D)
13
 ()

MHT-CET Triumph Chemistry (MCQs)

Shapes of atomie orbitals 56. Which of the following is INCORRECT flling
48. The value of azimuthal quantum number for the of electron in d-orbitals as per Hund's rule?
shape ot the orbital given below is (A)

(B)

(C) 1 ‘ 1
(D)

Electronic configuration of atomS and its

P- orbital
representation
(A) 0 (B) 57
(C) 1 (D) 3 The CORRECT electronic configuration of
Ti (Z = 22) atom is
49. Which d-orbital does NOT have four lobes? (A) 1s' 2s* 2p° 3s3p° 4s 3d'
(A) : (B) dyy (B) Is 2s 2p° 3s' 3p 3d
(C) Is' 2s? 2p 3s° 3p° 4s 3d
(C) dyz (D) d, (D) Is' 2s' 2p 3s° 3p° 4s' 3d
Energies of orbitals 58. The number of unpaired electrons in chromium
50. In a multi-electron atom, which of the following (Z=24) is
orbitals described by the three quantum numbers (A) 3 (B) 5 (C) 6 (D) 8
will have the same energy in the absence of 59. What is the total number of electrons present in
magnetic and electric fields? the p-orbitals of an atom having Z = 30?
(1) n=1,/=0, m= 0 (A) 6 (B) 11
(2) n=2,/=0, m=0 (C) 12 (D) 18
(3) n=3,/= 2, m=
(4) n=3,/= 2, m=1 60. Which of the following is an isoelectronic pair?
(A) (1) and (2) (B) (2) and (3) (A) Na', F (B) Ne, 0
(C) (1) and (3) (D) (3) and (4) (C) Na", Mg (D) Mg,o
51. Energy of atomic orbitals in a particular shell is Miscellaneous
in the order
61. The charge of an electron is -1.6 x 10 C. The
(A) s<p<d<f (B) s>p>d>f value of free charge on Li ion will be
(C) p<d<f<s (D) f>d>s>p (A) 3.6 x 10- c (B) lx 10-19 c
Aufbau principle (C) 1.6x 10 C (D) 2.6 x 10lc
52. When 3d orbitals are completely filled, new 62. The ratio of charge to mass would be greater for
electron will enter in orbitals.
(A) 4s (B) 4p (C) 4d (D) 4f (A) proton (B) electron
53. Which of the following sequence is CORRECT (C) neutron (D) alpha particle
as per Aufbau principle? 63. If n +7 = 6, then total possible number of
(A) 3s <3d < 4s < 4p subshells would be
(B) Is< 2p < 4s < 3d (A) 2 (B) 3 (C) 4 (D) 5
(C) 2s< 5s< 4p < 5d
64. The conclusion that heavier particles will
(D) 2s < 2p < 3d < 3p
54.
possess smaller wavelength as compared to
principle limits the number of lighter particles is derived from
electrons in any orbital of an atom. (A) Heisenberg's uncertainty principle
(A) Aufbau (B) Hund's (B) Einstein's photoelectric equation
(C) Pauli's exclusion (D) Allof these (C) de-Broglie equation
55. How many electrons in a given atom can have (D) Planck's quantum theory
the following set of quantum numbers? 65. Which of the tollowing has more electrons than
neutrons? (Mass number of Al, C, 0 and F is
n-3,/ =2, m= +2, s =
27, 12, 16 and 19 respectively).
(A) I (B) (A) A (B) C
(C) (D) I8 (C) o (D) F
14
 Chapter 04: Structure of Atom
00. The set of quantum numbersn=3, /= 0, m = 0, 4.2 Atomic number and atomic mass number
s=-1/2 represents an electron of the element
9. Atomic number of an clement is cqual to
(A) Mg (B) He
(C) Ne (D) F (A) the sum of the numbers of clectrons and
neutrons
1 the number of protons present in the
67. If an electron has spin quantum number of + (B)
nucleus of an atom of the element
and a magnetic quantum number -1, it (C) the number of neutrons present in the
CANNOT be present in the orbital. nucleus of an atom of the element
(A) d (B) f (D) the sum of the numbers of electrons and
(C) p (D) S protons
10. Mass number of an atom is equal to
Homework (A) proton number - neutron number
(B) proton number + neutron number
4.1 Subatomic particles
(C) number of nucleons - number of electrons
1. The protons and neutrons are collectively called (D) neutron number
as
11. The mass number and atomic number of an
(A) deuterons (B) positrons
(C) mesons (D) nucleons element are A and Z respectively. The number
of neutrons in the atomn of that element is
2 The mass of a proton is equal to calculated as
(A) 0.0055 u (B) 1.00727u (A) A (B) Z
(C) 1.6000 u (D) 1.672 u (C) A +Z (D) A -Z
3 Cathode rays are made up of 12. Select the INCORRECT statement.
(A) positively charged particles (A) The number of protons in the nucleus is
(B) negatively charged particles chemical identity of an element.
(C) neutral particles (B) The total electronic charge on an atom is
(D) equal amount of positively and negatively -Ze.
charged particles (C) The composition of any atom is
4. Name the particle that was identified by represented as x
JJ. Thomson in the cathode ray tube experiment. (D) The mass of an atom is concentrated in its
(A) Proton (B) Neutron nucleus.
(C) Nucleon (D) Electron
13. The nuclide having 6 protons and 8 neutrons is
5 Rutherford bombarded thin gold foil with represented as
(A) X (B)
(A) aparticles (B) Bparticles
(C) Yparticles (D) neutrons (C) (D) X

6. The element used by Rutherford to prepare thin 14 The number of neutrons in "C is
foil for his a-particle scattering experiment was (A) 6 (B) 7 (C) 8 (D) 9

(A) gold (B) tin 15. The number of protons, neutrons and electrons
(C) silver (D) lead in a neutral atom of the element 2x are 89

7. respectively.
An a-particle is represented as (A) 89, 89, 242 (B) 89, 142, 89
(A) a (B) a (C) 89, 71,89 (D) 89, 231, 89
(C) u (D) 'a
4.3 Isotopes, isobars and isotones
The electrically neutral and massive particle
which was predicted by Rutherford to account 16. Isotopes of an element have
for the disparity in atomic number and atomic (A) same number of neutrons
mass of' an element is (B) same number of protons
(A) proton (B) electron (C) same atomic mass number
(C) a-particle (D) Ileutron (D) same number of nucleons
15
MHT-CET Triumph Chemistry (Mcas)
17. Sclect the CORRECT option regarding the 27. Intensity of radiation is determined by
isotopes of carbon. of the wave.
(A) C is more abundant than "C. (A) frequency (B) wavelength
(B) C is the most stable isotope. (C) amplitude (D) velocity
(C) Cis more abundant than C. 6
28. The energy of one quantum of radiation is
(D) C and C are radioactive. calculated by
(A) E= hv (B) h= Ev
18. Isobars always have the same number of
(C) h= (D)
(A) protons (B) electrons
(C) nucleons (D) neutrons 29. The value of Planck's constant is
(A) 6.626 x 10*Js
19. Which of the following pairs represent isobars? 6.023 x 10 Js
(A) He and He (B)
(B) Mg and Mg 6.626 x 10- Js
(C)
(C) 9K and Ca (D) KandK (D) 6.626 x 10 Js
20. Isotones have 30. has the simplest emission spectrum.
(A) same number of neutrons
(A) Carbon (B) Hydrogen
(B) same number of protons (C) Sodium (D) Oxygen
(C) same number of electrons
(D) same number of nucleons 31. The value of Rydberg constant for hydrogen
atom is
21. Which of the following is an isotone of ";c? 109677 m!
(A)
(A) 'B (B) C (C) c (D) (B) 109677 cm
4.4 Drawbacks of Rutherford atomic model (C) 109677 x 10 cml
(D) 109677 x 10 cm!
22. Rutherford's model of an atom is unstable
because 32 The emission spectrum of hydrogen in the
(A) the proton is an unstable particle ultraviolet region of electromagnetic radiation
(B) the electron is an unstable particle forms series.
(C) the electron has very high kinetic energy (A) Pfund (B) Lyman
(D) an accelerated electron in an orbit emits (C) Balmer (D) Brackett
radiation
33. The spectral line obtained when an electron
4.5 Developments leading to the Bohr's atomic jumps from n = 6 to n = 3 level in hydrogen
model atom belongs to the series.
(A) Balmer (B) Lyman
23. When light interacts with matter, it behaves as a (C) Paschen (D) Pfund
stream of particles called and when
light propagates, it behaves as a/an 34. Which of the following is INCORRECT
(A) photons, electromagnetic wave regarding different series observed in hydrogen
(B) electromagnetic wave, atoms spectrum?
(C) cathode rays, electromagnetic wave (A) For Balmer series, n, =2.
(D) photons, electron (B) For Brackett series, n = 4.
24. The distance between two consecutive crests or (C) For Lyman series, n, = 1.
troughs is called (D) For Pfund series, n, = 3.
(A) Amplitude (B) Wavelength 4.6 Bohr's model for hydrogen atom
(C) Wavenumber (D) Frequency
35. According to Bohr's model for the hydrogen
25. The SI unit of frequency of radiation is atom, when electrons revolve in the stationary
orbits,
(A) cm (B) Hertz
(C) nm
(A) the energies of the electrons remain
(D) Imetre
constant
26. is the number of wavelengths per unit (B) they become stationary
length. (C) they gain potential energy
(A) Amplitude (B) Velocity (D) there is increase in energies of the
(C) Wavenumber (D) Frequency electrons
16
 Chapter 04: Structure of Atom
36. When an clectron jumps from K to L shell, 44. The de Broglie wavelength (0.) associated with a
energy is material particle is
(A) absorbed (A) directly proportional to its mass
(B) released (B) directly proportional to its momentum
(C) sometimes absorbed and sometimes (C) inversely proportional to h
released (D) inversely proportional to its momentum
(D) neither absorbed nÍr released 45. Heisenberg's uncertainty principle rules out the
exact simultaneous measurement of of
37. According to Bohr's theory, the angular
momentum of an electron in the fourth Bohr's a moving microscopicparticle.
orbit is (A) probability and intensity
(B) energy and momentum
h 2h
(A) (B) (C) charge density and radius
2T T
(D) position and momentum
3h 3h
(C) 2
(D) 46. Mathematically, Heisenberg's uncertainty
principle is expressed as
h h
38. The energy of an electron in the n orbit of (A) Ax x Ap, > (B) Ap, >
hydrogen atom is Ax
2.18x 10-18 Ar> p,Xh
(A) Jatom-! (C) Ax x Ap, > (D)
n 4 41

2.18 x 10-18 4.7 Quantum mechanical model of atom

(B) -Jatom-l
n

2.18 x 10-8
Schrodinger equation
(C) -Jatom! 47. In the Schrodinger wave equation, s represents
n'
-18
2.18 × 10
(D) J atom-! (A) orbit
(B) wave function
39. The ratio of radii of second and first Bohr's (C) energy of an electron
orbits of H-atom is (D) radial probability
(A) 2:1 (B) 1:3 Atomic orbitals and quantum numbers
(C) 4:1 (D) 2:3
48. How many quantum numbers are required to
40. The phenomenon of splitting of atomic spectral fully specify an electron in an atom?
lines under the influence of the external (A) One (B) Three
effect. (C) Two (D) Four
magnetic field is known as
(A) photoelectric (B) Stark 49. The principal quantum number 'n' describes the
(C) Zeeman (D) spectral
41.
(A) shape of the orbital
The splitting of atomic spectral lines in the (B) subshell to which the electron belongs
presence of external electric field is called (C) main shell to which the electron belongs
effect.
(D) spin of the electron
(A) Zeeman (B) Photoelectric
(C) Stark (D) none of these 50. The number of allowed orbitals in any principal
shell is given by
42. Which of the following represents the (A) (2l+ 1) (B) 2n
de Broglie relation? (C) (2n + 1) (D) n
(A) mv = hc/ (B) my = h/2
51. Maximum number of electrons that can be
h accommodated in Mshell is
(C) my = 2/h (D) A=
mvc (A) 18 (B) 32 (C) 2 (D)
43. The de Broglie equation suggests that an 52. The value /= Irepresents subshell.
electron has nature. (A) (B) p (C) (D) f
(A) only particle 53. The quantum numbers n = $, != 3 represent the
(B) only wave orbital.
(C) particle as well as wave (A) Ss (B)
(D) none of these (C) Sd (D) Sp
17
MHT-CET Triumph Chemistry (MCQs)
$4. The total number of subshells in the N shell is (C) The electron cloud of 2s orbital shows
two nodes.
(A) 3 (B) 4 (D) The probability of finding an electron at
(C) S (D) 7 a given point in an atomn is proportional
to !.
$5. The number of orbitals in a subshell is equal to
63. A node is a region with nearly
(A) n (B) 21 probability density.
(C) (2/+ 1) (A) zero (B) S0%
(D) 2(n-) (C) 75% (D) 100%
56. The maximum number of electrons in s, p and 64. The shape of s-orbital is
d-subshells are respectively. (A) pyramidal (B) spherical
(A) 2, 2 and 4 (B) 2, 4 and 6 (C). tetrahedral
(C) 2, 6and 10 (D) 2,6 and 12 (D) trigonal
65. For s-orbitals, as the value of n increases, the
57. The maximum number of electrons that can be size of the s-orbital
accommodated in f-subshell is
(A) increases
(A) 2 (B) (B) decreases
(C) 14 (D) 32 (C) remains the same
(D) first increases then decreases
58. Which of the following orbitals does NOT
exist? 66. Each p-orbital has lobe(s) on the two
(A) 3d (B) 3f sides of a nodal plane passing through the
(C) 5p (D) 7s nucleus.
(A) zero (B) one
59. When the value of azimuthal quantum number is (C) two (D) three
3, magnetic quantum number can have values
67. 2p, and 2p, orbitals differ in their
(A) +1, 0, - 1 (A) orientation (B) energy
(B) +2, + 1, 0, 1, -2 (C) shape (D) T value
(C) -3, - 2, - 1, -0, + 1, + 2, + 3 68. Which of the following is INCORRECT?
(D) +1,-1 (A) d-orbitals have 3 orientations.
60.
(B) Each p-orbital resembles a dumb-bell.
The spin quantum numbers of two electrons
Occupying the same orbital are (C) d. is dumb-bell shaped and lies along
(A) +1l and -1 (B) 0 and + 1 the x and y axes.
(D) The three p-orbitals are perpendicular to
(C) +2 and -2 (D) *,and each other.
2
69. Which orbital is double dumb-bell shaped?
61. Which of the following is CORRECT?
(A) S-orbital (B) dyyorbital
(A) Azimuthal quantum number () can have
(C) p-orbital (D) P, -orbital
only positive values between 0 and -l.
(B) Electron spin quantum number describes Energies of orbitals
the shape of the orbital that is occupied by 70.
the electron. For hydrogen atom, which of the following has
the lowest energy?
(C) Principal quantum number describes the (A) 2p (B) 3s
relative spatial orientation of the orbitals
in a given subshell.
(C) 4s (D) 3p
(D) Magnetic orbital quantum number has 71. Which of the following is CORRECT?
values from -/ to +/ through zero. (A) The orbitals with the same energy and the
corresponding wave funetions being
Shapes of atomie orbitals different are called degenerate orbitals.
(B) The ground state of an atom corresponds
62. Which of the following is CORRECT? to the highest total electronic energy.
(A) Aboundary surface diagram encloses a (C) If two orbitals have the same (n + )
region where the probability of finding values then orbital with the higher value
electron is typically more than 50%. of n is of lower energy.
(B) A boundary surface diagram is a good (D) In hydrogen atom, 2s and 2p are not
representation of shape of an orbital. degenerate orbitals.
18
 Chapter 04: Structure of Atom
Aufbau principle 79. The number of unpaired clectrons in Is' 2s 2p
72. gives orbital wise distribution of 2 (C) I (D) 0
clectrons in the ground state of an atom. (A) 4 (B)
(A) Heisenberg principle 80. The total number of unpaired electrons in
(B) Aufbau principle the d-orbitals of an atom of the element with
(C) Pauli's exclusion principle atomic number 29 is
(D) Hund's rule (A) 10 (B) (C) 0 (D) 5
73. Hund's rule deals with the distribution of 81. Electronic configuration of H is
electrons in (A) 1s° (B) 1s
(A) aprincipal shell (C) 1s² (D) Is' 2s'
(B) different subshells
(C) orbitals with slightly different energies 82. Which of the following is isoelectronic with K´?
(D) degenerate orbitals (A) Ar (B) Ca (C) Sc (D) s
74. In which of the following electron distributions Miscellaneous
in ground state, the Hund's rule and Aufbau 83. Which of the following statements
principle is NOT violated?
INCORRECT?
2s 2p
(A) (A) Electrons behave as particles.
1 (B) Electrons have wave character.
(C) Electrons give a diffraction pattern.
2s 2p (D) Electrons lose energy while revolving in
orbits.
(B)
2s 2p 84. Neutrons are present in all atoms EXCEPT
(C) (A) }H (B) C (C) H (D) Be
2s 2p 85. How many electrons in jgK have n =3, I= 0?
(D)1 (A) 1 (B) 2 (C) 4 (D) 3
86. 36Kr has the electronic configuration as
Electronic configuration of atoms and its
[Ar] 4s 3d" 4p°. The next electron will go into
representation the orbital.
75. Electronic configuration of C in orbital notation (A) 4d (B) 4f (C) 5s (D) 6s
method is
87. Match the following:
(A) 1s' 2s 2p (B) 1s' 2s° 2p
(C) 1s' 2s (D) 1s' 2s2p Column I Column II
76. Which of the following electronic configuration Heisenberg's equation a. h
is CORRECT for iron? mv

(A) 1s 2s 2p° 3s3p° 3d de Broglie's equation b.

(B) 1s' 2s* 2p° 3s 3p° 4s 3d' iii. Bohr's frequency rule C. E= hy
(C) Is 2s* 2p° 3s* 3p° 4s'3d' iv. Planck's equation d. v=E-E,
(D) Is' 2s' 2p° 3s 3p° 4s 3d°
77. The CORRECT orbital diagram for beryllium (A) i-d, ii - b, ii- a, iv -c
atom in ground state is
(B) i-b, ii - c, ii - d, iv - a
(A) (B) (C) i-c, ii - a, ii - b, iv -d
(D) i-b, ii - a, iii d, iv - c
ls 2s 1s 2s
88. Find the INCORRECT statement.
(C) (D)
(A) The SI unit of wavenumber is m
Is 2% 2s (B) Angular momentum is a produet of
moment of inertia and angular velocity.
78. Which of the following electronic (C) According to Bohr's theory, stationary
configurations is NOT possible in the ground states with higher values of 'n' have large
state of an alom? and negative energy.
(A) Is 2s (B) Is 2s 2p° (D) In vacuum, the speed of all the types of
(C) Is' 2s 2p (D) Is 2s' 2p 3s' electromagnetic radiation is the same.
19
MHT-CET Triumph Chemistry (MCQs)

Answer Key

Classwork
1 (C) 2. 3.
(B) (A) 4. (B) 5. (B) 6. (D) 7. (A) 8. (C) 9. (B) 10. (D)
11. (B) 12. (D) 13. (A) 14. (C) 15. (C) 16. (C) 17. (C) 18 (C) 19. (A) 20. (D)
21. (A) 22. (D) 23. (D) 24. (D) 25. . (D) 26. (A) 27. (B) 28. (A) 29. (C) 30. (C)
31. (D) 32. (D) 33. .(A) 34. (B) 35. (C) 36. (A) 37. (C) 38. (A) 39. (C) 40. (A)
41. (D) 42. (D) 43. (C) 44. (D) 45. (C) 46. (A) 47. (A) 48. (C) 49. (D) 50. (D)
51. (A) 52. (B) 53. (B) 54. (C) 55. (A) 56. (B) 57. (A) 58. (C) s9. (C) 60. (B)
61. (C) 62. (B) 63. (B) 64. (C) 65. (C) 66. (A) 67. (D)

Homework
(D) 2. (B) 3. (B) 4. (D) 5. (A) 6. (A) 7. (B) 8. (D) 9. (B) 10. (B)
11. (D) 12. 13. (A) l4. (A) 15. (B) 16 (B) 17. (A) 18. (C) 19. (C) 20. (A)
(C)
21. (A) 22. (D) 23. (A) 24. (B) 25. (B) 26. (C) 27. (C) 28. (A) 29. (A) 30. (B)
31. (B) 32. (B) 33. (C) 34. (D) 35. (A) 36. (B) 38. (C) 39.
(A) 37. (C) 40. (C)
41. (C) 42. (B) 43. (C) 44. (D) 45. (D) 46.
(C) 47. (B) 48. (D) 49. (C) 50. (D)
51. (A) S2. (B) 53. (B) 54. (B) 55. (C) 57. (C) 58. (B) 59.
(C) 56. (C) 60. (D)
61. (D) 62. (B) 63. (A) 64. (B) 65. (A) 66. (C) 67. (A) 68. (A) 69. (B) 70. (A)
71. (A) 72. (B) 73. (D) 74. (D) 75. (A) 76. (D) 77. (C) 78. (D) 79. (B) 80 (C)
81. (C) 82. (A) 83. (D) 84. (C) 85. (B) 86. (C) 87. (D) 88. (C)

20