Atoms Practice Questions - DPP for NEET

 Page 1


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 In nature there may not be an element for which the
principal quantum number 
4 n >
, then the total possible
number of elements will be
(a) 60 (b) 32 (c)4 (d) 64
Q.2 In the following atoms and molecule  for the transition
from 
2 n =
to 
1 n =
, the spectral line of minimum
wavelength will be produced by
(a) Hydrogen atom (b) Deuterium atom
(c) Uni-ionized helium (d) Di-ionized lithium
Q.3 The Lyman series of hydrogen sperctum lies in the region
(a) Infrared (b) Visible
(c) Ultraviolet (d) X - rays
Q.4 The energy levels of the hydrogen spectrum is shown in
figure. There are some transitions. A,B,C,D and E.
Transition , AB and 
C
respectively represent
(a) First spectral line of
Lyman series, third
spectral line of Balmer
series and the second
spectral line of Paschen
series.
(b) Ionization potential of hydrogen, second spectral line
of Balmer series and third spectral line of Paschen
series
(c) Series limit of Lyman series, third spectral line of
Balmer series and second spectral line of Paschen
series
(d) Series limit of Lyman series, second spectral line of
Balmer series and third spectral line of Paschen series
Page 2


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 In nature there may not be an element for which the
principal quantum number 
4 n >
, then the total possible
number of elements will be
(a) 60 (b) 32 (c)4 (d) 64
Q.2 In the following atoms and molecule  for the transition
from 
2 n =
to 
1 n =
, the spectral line of minimum
wavelength will be produced by
(a) Hydrogen atom (b) Deuterium atom
(c) Uni-ionized helium (d) Di-ionized lithium
Q.3 The Lyman series of hydrogen sperctum lies in the region
(a) Infrared (b) Visible
(c) Ultraviolet (d) X - rays
Q.4 The energy levels of the hydrogen spectrum is shown in
figure. There are some transitions. A,B,C,D and E.
Transition , AB and 
C
respectively represent
(a) First spectral line of
Lyman series, third
spectral line of Balmer
series and the second
spectral line of Paschen
series.
(b) Ionization potential of hydrogen, second spectral line
of Balmer series and third spectral line of Paschen
series
(c) Series limit of Lyman series, third spectral line of
Balmer series and second spectral line of Paschen
series
(d) Series limit of Lyman series, second spectral line of
Balmer series and third spectral line of Paschen series
2
DPP/ P 55
Q.5 Energy levels A, B, C of a certain atom corresponding to
increasing values of energy i.e. 
ABC
EEE << . If
1 23
,, l ll are the wavelengths of radiations corresponding
to the transitions C to B, B to A and C to A respectively,
which of the following statements is correct?
C
B
A
1
l
2
l
3
l
(a)
3 12
l = l +l (b)
12
3
12
ll
l=
l +l
(c)
123
0 l +l +l= (d)
2 22
3 12
l = l +l
Q.6 If m is mass of electron, v its velocity, r the radius of
stationary circular orbit around a nucleus with charge Ze,
then from Bohr’s first postulate, the kinetic energy
2
1
2
= K mv of the electron in 
. .. CGS
 system is equal to
(a)
2
1
2
Ze
r
(b)
2
2
1
2
Ze
r
(c)
2
Ze
r
(d)
2
Ze
r
Q.7 When a hydrogen atom is raised from the ground state to
an excited state
(a) P. E. increases and K. E. decreases
(b) P. E. decreases and K. E. increases
(c) Both kinetic energy and potential energy increase
(d) Both K. E. and P. E. decrease
Q.8 The value of the kinetic energy divided by the total energy
of an electron in a Bohr orbit is
(a) – 1 (b)2
(c) 0.5 (d) None of these
Q.9 The ratio of the frequencies of the long wavelength limits
of Lyman and Balmer series of hydrogen spectrum is
(a) 27 : 5 (b) 5 : 27
(c) 4 : 1 (d) 1 : 4
Q.10 Ratio of the wavelengths of first line of Lyman series and
first line of Balmer series is
(a) 1 : 3 (b) 27 : 5 (c) 5 : 27 (d) 4 : 9
Q.11 According to Bohr’s theory the moment of momentum of
an electron revolving in second orbit of hydrogen atom will
be
(a)
2 h p
(b) 
h p
(c)
h
p
(d)
h
p
Q.12 In the Bohr model of a hydrogen atom, the centripetal force
is furnished by the coulomb attraction between the proton
and the electron. If 
0
a is the radius of the ground state orbit,
m is the mass, e is the charge on the electron and 
0
e is the
vacuum permittivity, the speed of the electron is
(a)0 (b)
00
e
am e
(c)
00
4
e
am pe
(d)
00
4 am
e
pe
Q.13 Which of the following transitions in hydrogen atoms emit
photons of highest frequency?
(a) n = 1 to n = 2 (b) n = 2 to n = 6
(c) n = 6 to n = 2 (d) n = 2 to n = 1
Q.14 As per Bohr model, the minimum energy (in 
eV
) required
to remove an electron from the ground state of doubly
ionized Li atom ( 3) Z = is
(a) 1.51 (b) 13.6
(c) 40.8 (d) 122.4
Q.15The third line of Balmer series of an ion equivalent to
hydrogen atom has wavelength of 108.5 nm. The ground
state energy of an electron of this ion will be
(a) 3.4 eV (b) 13.6 eV
(c) 54.4 eV (d) 122.4 eV
Q.16 The wavelength of radiation emitted is 
0
l when an electron
jumps from the third to the second orbit of hydrogen atom.
For the electron jump from the fourth to the second orbit of
the hydrogen atom, the wavelength of radiation emitted will
be
(a)
0
16
25
l
(b)
0
20
27
l
(c)
0
27
20
l
(d)
0
25
16
l
Page 3


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 In nature there may not be an element for which the
principal quantum number 
4 n >
, then the total possible
number of elements will be
(a) 60 (b) 32 (c)4 (d) 64
Q.2 In the following atoms and molecule  for the transition
from 
2 n =
to 
1 n =
, the spectral line of minimum
wavelength will be produced by
(a) Hydrogen atom (b) Deuterium atom
(c) Uni-ionized helium (d) Di-ionized lithium
Q.3 The Lyman series of hydrogen sperctum lies in the region
(a) Infrared (b) Visible
(c) Ultraviolet (d) X - rays
Q.4 The energy levels of the hydrogen spectrum is shown in
figure. There are some transitions. A,B,C,D and E.
Transition , AB and 
C
respectively represent
(a) First spectral line of
Lyman series, third
spectral line of Balmer
series and the second
spectral line of Paschen
series.
(b) Ionization potential of hydrogen, second spectral line
of Balmer series and third spectral line of Paschen
series
(c) Series limit of Lyman series, third spectral line of
Balmer series and second spectral line of Paschen
series
(d) Series limit of Lyman series, second spectral line of
Balmer series and third spectral line of Paschen series
2
DPP/ P 55
Q.5 Energy levels A, B, C of a certain atom corresponding to
increasing values of energy i.e. 
ABC
EEE << . If
1 23
,, l ll are the wavelengths of radiations corresponding
to the transitions C to B, B to A and C to A respectively,
which of the following statements is correct?
C
B
A
1
l
2
l
3
l
(a)
3 12
l = l +l (b)
12
3
12
ll
l=
l +l
(c)
123
0 l +l +l= (d)
2 22
3 12
l = l +l
Q.6 If m is mass of electron, v its velocity, r the radius of
stationary circular orbit around a nucleus with charge Ze,
then from Bohr’s first postulate, the kinetic energy
2
1
2
= K mv of the electron in 
. .. CGS
 system is equal to
(a)
2
1
2
Ze
r
(b)
2
2
1
2
Ze
r
(c)
2
Ze
r
(d)
2
Ze
r
Q.7 When a hydrogen atom is raised from the ground state to
an excited state
(a) P. E. increases and K. E. decreases
(b) P. E. decreases and K. E. increases
(c) Both kinetic energy and potential energy increase
(d) Both K. E. and P. E. decrease
Q.8 The value of the kinetic energy divided by the total energy
of an electron in a Bohr orbit is
(a) – 1 (b)2
(c) 0.5 (d) None of these
Q.9 The ratio of the frequencies of the long wavelength limits
of Lyman and Balmer series of hydrogen spectrum is
(a) 27 : 5 (b) 5 : 27
(c) 4 : 1 (d) 1 : 4
Q.10 Ratio of the wavelengths of first line of Lyman series and
first line of Balmer series is
(a) 1 : 3 (b) 27 : 5 (c) 5 : 27 (d) 4 : 9
Q.11 According to Bohr’s theory the moment of momentum of
an electron revolving in second orbit of hydrogen atom will
be
(a)
2 h p
(b) 
h p
(c)
h
p
(d)
h
p
Q.12 In the Bohr model of a hydrogen atom, the centripetal force
is furnished by the coulomb attraction between the proton
and the electron. If 
0
a is the radius of the ground state orbit,
m is the mass, e is the charge on the electron and 
0
e is the
vacuum permittivity, the speed of the electron is
(a)0 (b)
00
e
am e
(c)
00
4
e
am pe
(d)
00
4 am
e
pe
Q.13 Which of the following transitions in hydrogen atoms emit
photons of highest frequency?
(a) n = 1 to n = 2 (b) n = 2 to n = 6
(c) n = 6 to n = 2 (d) n = 2 to n = 1
Q.14 As per Bohr model, the minimum energy (in 
eV
) required
to remove an electron from the ground state of doubly
ionized Li atom ( 3) Z = is
(a) 1.51 (b) 13.6
(c) 40.8 (d) 122.4
Q.15The third line of Balmer series of an ion equivalent to
hydrogen atom has wavelength of 108.5 nm. The ground
state energy of an electron of this ion will be
(a) 3.4 eV (b) 13.6 eV
(c) 54.4 eV (d) 122.4 eV
Q.16 The wavelength of radiation emitted is 
0
l when an electron
jumps from the third to the second orbit of hydrogen atom.
For the electron jump from the fourth to the second orbit of
the hydrogen atom, the wavelength of radiation emitted will
be
(a)
0
16
25
l
(b)
0
20
27
l
(c)
0
27
20
l
(d)
0
25
16
l
DPP/ P 55
3
Q.17The energy of electron in the 
th
n
orbit of hydrogen atom
is expressed as 
2
13.6
n
E eV
n
-
=
. The shortest and longest
wavelength of Lyman series will be
(a) 910 Å, 1213 Å (b) 5463 Å, 7858 Å
(c) 1315 Å , 1530 Å (d) None of these
Q.18 Consider a hydrogen like atom whose energy in 
th
n
exicited
state is given by 
2
2
13.6
n
Z
E
n
=- when this excited atom
makes a transition from excited state to ground state, most
energetic photons have energy 
max
52.224 E eV = and least
energetic photons have energy 
min
1.224 E eV = . The
atomic number of atom is
(a)2 (b)5
(c)4 (d) None of these
Q.19In the Bohr model of the hydrogen atom, let R, v and E
represent the radius of the orbit, the speed of electron and
the total energy of the electron respectively. Which of the
following quantity is proportional to the quantum number
n
(a) / RE (b) / Ev
(c) RE (d)
vR
Q.20 An a- particle of 5 
MeV
energy strikes with a nucleus
of uranium at stationary at an scattering angle of 180°. The
nearest distance upto which a- particle reaches the
nucleus will be closest to
(a) 1 Å (b) 10
–10
cm
(c) 10
–12
cm (d) 10
–15
cm
Q.21 In a hypothetical Bohr hydrogen, the mass of the electron
is doubled. The energy 
0
E and the radius 
0
r of the first
orbit will be (
0
a is the Bohr radius)
(a)
0 00
27.2 ; /2 E eVra =-=
(b)
0 00
27.2; E eVra =-=
(c)
0 00
13.6 ; /2 E eVra =-=
(d)
0 00
13.6; E eVra =-=
DIRECTIONS (Q.22-Q.24) : In the following questions,
more than one of the answers  given are correct. Select
the correct answers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.22 The electron in a hydrogen atom makes a transition n
1
 ®
n
2
, where n
1
 and n
2
 are the principal quantum numbers of
two states. Assume the Bohr model to be valid. The time
period of the electron in the initial state is eight times that
in the final state. Then
(1) n
1 
= 4 (2) n
2 
= 2 (3) n
2 
= 5 (4) n
1 
= 5
Q.23 A free hydrogen atom in ground state is at rest. A neutron
of kinetic energy K collides with the hydrogen atom.
After collision hydrogen atom emits two photons in
succession one of which has energy 2.55eV. Assume that
the hydrogen atom and neutron has same mass.
(1) Minimum value of K is 25.5 eV
(2) Minimum value of K is 12.75 eV
(3) The other photon has energy 10.2eV
(4) The upper energy level is of excitation energy 12.5
eV
Q.24Which of the series of hydrogen spectrum are not in the
visible region?
(1) Lyman series (2) Paschen series
(3) Bracket series (4) Balmer series
DIRECTIONS (Q.25-Q.27) : Read the passage given below
and answer the questions that follows :
A gas of identical hydrogen like atoms has some atoms in ground
state and some atoms in a particular excited state and there are
no atoms in any other energy level. The atoms of the gas make
transition to a higher energy state by absorbing monochromatic
light of wavelength 304Å. Subsequently, the atoms emit radia-
tion of only six different photon energies. Some of emitted pho-
tons have wavelength 304 Å, some have wavelength more and
some have less than 304Å (Take hc = 12420 eV–Å)
Q.25 Find the principal quantum number of the initially excited
state.
(a)1 (b)2 (c)3 (d)4
Page 4


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 In nature there may not be an element for which the
principal quantum number 
4 n >
, then the total possible
number of elements will be
(a) 60 (b) 32 (c)4 (d) 64
Q.2 In the following atoms and molecule  for the transition
from 
2 n =
to 
1 n =
, the spectral line of minimum
wavelength will be produced by
(a) Hydrogen atom (b) Deuterium atom
(c) Uni-ionized helium (d) Di-ionized lithium
Q.3 The Lyman series of hydrogen sperctum lies in the region
(a) Infrared (b) Visible
(c) Ultraviolet (d) X - rays
Q.4 The energy levels of the hydrogen spectrum is shown in
figure. There are some transitions. A,B,C,D and E.
Transition , AB and 
C
respectively represent
(a) First spectral line of
Lyman series, third
spectral line of Balmer
series and the second
spectral line of Paschen
series.
(b) Ionization potential of hydrogen, second spectral line
of Balmer series and third spectral line of Paschen
series
(c) Series limit of Lyman series, third spectral line of
Balmer series and second spectral line of Paschen
series
(d) Series limit of Lyman series, second spectral line of
Balmer series and third spectral line of Paschen series
2
DPP/ P 55
Q.5 Energy levels A, B, C of a certain atom corresponding to
increasing values of energy i.e. 
ABC
EEE << . If
1 23
,, l ll are the wavelengths of radiations corresponding
to the transitions C to B, B to A and C to A respectively,
which of the following statements is correct?
C
B
A
1
l
2
l
3
l
(a)
3 12
l = l +l (b)
12
3
12
ll
l=
l +l
(c)
123
0 l +l +l= (d)
2 22
3 12
l = l +l
Q.6 If m is mass of electron, v its velocity, r the radius of
stationary circular orbit around a nucleus with charge Ze,
then from Bohr’s first postulate, the kinetic energy
2
1
2
= K mv of the electron in 
. .. CGS
 system is equal to
(a)
2
1
2
Ze
r
(b)
2
2
1
2
Ze
r
(c)
2
Ze
r
(d)
2
Ze
r
Q.7 When a hydrogen atom is raised from the ground state to
an excited state
(a) P. E. increases and K. E. decreases
(b) P. E. decreases and K. E. increases
(c) Both kinetic energy and potential energy increase
(d) Both K. E. and P. E. decrease
Q.8 The value of the kinetic energy divided by the total energy
of an electron in a Bohr orbit is
(a) – 1 (b)2
(c) 0.5 (d) None of these
Q.9 The ratio of the frequencies of the long wavelength limits
of Lyman and Balmer series of hydrogen spectrum is
(a) 27 : 5 (b) 5 : 27
(c) 4 : 1 (d) 1 : 4
Q.10 Ratio of the wavelengths of first line of Lyman series and
first line of Balmer series is
(a) 1 : 3 (b) 27 : 5 (c) 5 : 27 (d) 4 : 9
Q.11 According to Bohr’s theory the moment of momentum of
an electron revolving in second orbit of hydrogen atom will
be
(a)
2 h p
(b) 
h p
(c)
h
p
(d)
h
p
Q.12 In the Bohr model of a hydrogen atom, the centripetal force
is furnished by the coulomb attraction between the proton
and the electron. If 
0
a is the radius of the ground state orbit,
m is the mass, e is the charge on the electron and 
0
e is the
vacuum permittivity, the speed of the electron is
(a)0 (b)
00
e
am e
(c)
00
4
e
am pe
(d)
00
4 am
e
pe
Q.13 Which of the following transitions in hydrogen atoms emit
photons of highest frequency?
(a) n = 1 to n = 2 (b) n = 2 to n = 6
(c) n = 6 to n = 2 (d) n = 2 to n = 1
Q.14 As per Bohr model, the minimum energy (in 
eV
) required
to remove an electron from the ground state of doubly
ionized Li atom ( 3) Z = is
(a) 1.51 (b) 13.6
(c) 40.8 (d) 122.4
Q.15The third line of Balmer series of an ion equivalent to
hydrogen atom has wavelength of 108.5 nm. The ground
state energy of an electron of this ion will be
(a) 3.4 eV (b) 13.6 eV
(c) 54.4 eV (d) 122.4 eV
Q.16 The wavelength of radiation emitted is 
0
l when an electron
jumps from the third to the second orbit of hydrogen atom.
For the electron jump from the fourth to the second orbit of
the hydrogen atom, the wavelength of radiation emitted will
be
(a)
0
16
25
l
(b)
0
20
27
l
(c)
0
27
20
l
(d)
0
25
16
l
DPP/ P 55
3
Q.17The energy of electron in the 
th
n
orbit of hydrogen atom
is expressed as 
2
13.6
n
E eV
n
-
=
. The shortest and longest
wavelength of Lyman series will be
(a) 910 Å, 1213 Å (b) 5463 Å, 7858 Å
(c) 1315 Å , 1530 Å (d) None of these
Q.18 Consider a hydrogen like atom whose energy in 
th
n
exicited
state is given by 
2
2
13.6
n
Z
E
n
=- when this excited atom
makes a transition from excited state to ground state, most
energetic photons have energy 
max
52.224 E eV = and least
energetic photons have energy 
min
1.224 E eV = . The
atomic number of atom is
(a)2 (b)5
(c)4 (d) None of these
Q.19In the Bohr model of the hydrogen atom, let R, v and E
represent the radius of the orbit, the speed of electron and
the total energy of the electron respectively. Which of the
following quantity is proportional to the quantum number
n
(a) / RE (b) / Ev
(c) RE (d)
vR
Q.20 An a- particle of 5 
MeV
energy strikes with a nucleus
of uranium at stationary at an scattering angle of 180°. The
nearest distance upto which a- particle reaches the
nucleus will be closest to
(a) 1 Å (b) 10
–10
cm
(c) 10
–12
cm (d) 10
–15
cm
Q.21 In a hypothetical Bohr hydrogen, the mass of the electron
is doubled. The energy 
0
E and the radius 
0
r of the first
orbit will be (
0
a is the Bohr radius)
(a)
0 00
27.2 ; /2 E eVra =-=
(b)
0 00
27.2; E eVra =-=
(c)
0 00
13.6 ; /2 E eVra =-=
(d)
0 00
13.6; E eVra =-=
DIRECTIONS (Q.22-Q.24) : In the following questions,
more than one of the answers  given are correct. Select
the correct answers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.22 The electron in a hydrogen atom makes a transition n
1
 ®
n
2
, where n
1
 and n
2
 are the principal quantum numbers of
two states. Assume the Bohr model to be valid. The time
period of the electron in the initial state is eight times that
in the final state. Then
(1) n
1 
= 4 (2) n
2 
= 2 (3) n
2 
= 5 (4) n
1 
= 5
Q.23 A free hydrogen atom in ground state is at rest. A neutron
of kinetic energy K collides with the hydrogen atom.
After collision hydrogen atom emits two photons in
succession one of which has energy 2.55eV. Assume that
the hydrogen atom and neutron has same mass.
(1) Minimum value of K is 25.5 eV
(2) Minimum value of K is 12.75 eV
(3) The other photon has energy 10.2eV
(4) The upper energy level is of excitation energy 12.5
eV
Q.24Which of the series of hydrogen spectrum are not in the
visible region?
(1) Lyman series (2) Paschen series
(3) Bracket series (4) Balmer series
DIRECTIONS (Q.25-Q.27) : Read the passage given below
and answer the questions that follows :
A gas of identical hydrogen like atoms has some atoms in ground
state and some atoms in a particular excited state and there are
no atoms in any other energy level. The atoms of the gas make
transition to a higher energy state by absorbing monochromatic
light of wavelength 304Å. Subsequently, the atoms emit radia-
tion of only six different photon energies. Some of emitted pho-
tons have wavelength 304 Å, some have wavelength more and
some have less than 304Å (Take hc = 12420 eV–Å)
Q.25 Find the principal quantum number of the initially excited
state.
(a)1 (b)2 (c)3 (d)4
4
DPP/ P 55
Q.26 Identify the gas (Z = ?)
(a)1 (b)2 (c)3 (d)4
Q.27Find the maximum and minimum energies of emitted
photons (in eV)
(a) 20.4, 10.6 (b) 10.4, 3.6
(c) 40.8, 10.6 (d) None of these
DIRECTIONS (Q.28-Q.30) : Each of these questions contains
two statements: Statement-1 (Assertion) and Statement-2
(Reason). Each of these questions has four alternative choices,
only one of which is the correct answer. You have to select
the correct choice.
(a) Statement-1 is True, Statement-2 is True; Statement-2 is a
correct explanation for  Statement-1.
(b) Statement-1 is True, Statement-2 is True; Statement-2 is
NOT a correct explanation for Statement-1.
(c) Statement -1 is False, Statement-2 is True.
(d) Statement -1 is True, Statement-2 is False.
Q.28 Statement-1 : Bohr postulated that the electrons in
stationary orbits around the nucleus do not radiate energy .
Statement-2 : According to classical physics all moving
electrons radiate energy.
Q.29 Statement-1 : The force of repulsion between atomic
nucle us and a-particle varies with distance according to
inverse square law.
Statement-2 : Rutherford did a-particle scattering
experiment.
Q.30Statement-1 : Hydrogen atom consists of only one
electron but its emission spectrum has many lines.
Statement-2 : Only Lyman series is found in the absorption
spectrum of hydrogen atom whereas in the emission
spectrum, all the series are found.