Solved Examples

Ex.1 Complete the following table – Here m = mass of electron

Atom Atomic Mass Proton Neutron Elect r = radius of 3rd orbit
/ ion Number No. (p) (n) ron According to de-Broglie equation
(Z) (A) (e)
= = × =
Al3+ 13 14
Cu 29 63
Mg2+ 12 24 = ×3=3
Sr 88 38
Sol. (i) Atomic number (Z) = 13 = Number of Ex.4 The ionization energy of He+ is 19.6 × 10–18 J
protons atom–1. The energy of the first stationary state
Number of electrons = 13 –3 = 10
of Li+2 will be -
Mass number = n + p = 14 + 13 = 27
(A) 21.2 × 10–18 J/atom
(ii) Atomic number = Number of protons
= Number of electrons = 29 (B) 44.10 × 10–18 J/atom
Mass number = n + p = 63 (C) 63.2 × 10–18 J/atom
since p = 29 (D) 84.2 × 10–18 J/atom (Ans. B)
 n = 63 – p = 63 – 29 = 34 Sol. E1 for Li+2 = E1 for H × Z2 Li = E1 for H × 9
(iii) Number of protons = Z = 12 & Number of
E1 for He+ = E1 for H × Z2 He = E1 for H × 4
electrons = 12 – 2 = 10
Mass number = n + p = 24 or E1 for Li+2 = E1 for He+
 n = 24 – p = 24 – 12 = 12
(iv) Number of electrons = Number of protons
= Z = 38 = 19.6 × 10–18 ×
Mass number = n + p = 88
= 44.10 × 10–18 J/atom
 n = 88 – p = 88 – 38
= 50 Ex.5 The ionization energy of hydrogen atom is
13.6 eV. What will be the ionization energy of
Ex.2 An oil drop has 6.39 × 10 – 19 C charge. Find out
the number of electrons in this drop - He+ -
Sol. Charge on oil drop = 6.39 × 10– 19 C Sol. He+ is a hydrogen like species i.e. the electron is
Now we know that ionised from first orbit.
1.602 × 10– 19 C is the charge on one electron
 Ionization energy of He+ =
 6.39 × 10– 19 C will be charge on

= =

= 4 electrons = 54.4 eV

Ex.3 Find out the number of waves made by a Bohr Ex.6 The ionization energy of H-atom is 13.6 eV.
electron in one complete revolution in its The ionization energy of Li+2 ion will be -
3rdorbit of hydrogen atom – (A) 13.6 eV
Sol. Total no. of waves (B) 27.2 eV
= = (C) 54.4 eV
(D) 122.4 eV (Ans D)

Velocity of the electron in 3rd orbit = Sol. E1 for Li+2 = E1 for H × Z2 [for Li, Z = 3]
= 13.6 × 9 = 122.4 eV
ATOMIC STRUCTURE 30
 = 11180 KJ mol–1
Ex.7 Which transition of the Hydrogen spectrum
would have the same wave length as the Balmer Ex.9 Calculate the energy emitted when electron of
transition, n = 4 to n = 2 of He+ spectrum - 1.0 g atom of hydrogen undergo transition
(A) n2 = 2 to n1 = 1 giving the spectral line of lowest energy in the
visible region of its atomic spectrum -
(B) n2 = 3 to n1 = 1
(RH = 1.1 × 107 m–1, c = 3 × 10 8 ms–1,
(C) n2 = 4 to n1 = 2
h = 6.62 × 10–34 Js).
(D) n2 = 5 to n1 = 3 (Ans. A) Sol. The spectral line lies in the visible region i.e., it
Sol. +
For He ion, we have corresponds to the Balmer series i.e. n 1 = 2 and
hence n2 = 3, 4, 5, etc.
= R H Z2 For lowest energy n2 = 3
Substituting the values in the following relation.
= RH[2]2
= RH

= RH …(A)
= 1.1 × 107 ×
Now for H atom
= 1.1 × 107 ×
= RH …(B)

= = 6.55 × 10–

Equating equs (A) and (B) we have
7m
– =
Now we know that
Obviously n1 = 1 and n2 = 2. Hence the
E = h = h ×
transition n = 2 to n = 1 in hydrogen atom will
have the same wave length as the transition
= =3.03 × 10–19 J
n = 4 to n = 2 in He+ species.
 Energy corresponding to 1g atom of
Ex.8 Given R = 1.0974 × 107 m–1 and h = 6.626 × hydrogen
10– 34 Js. The ionization energy of one mole of = 3.03 × 10– 19 × 6.02 × 1023
Li+2 ions will be as follows - = 18.25 × 104 J = 182.5 KJ
(A) 11240 KJ mole–1
Ex.10 Estimate the difference in energy between 1 st
(B) 11180 KJ mole–1
and 2nd Bohr orbit for a H atom. At what
(C) 12350 KJ mole–1 minimum atomic no., a transition from n = 2 to
(D) 15240 KJ mole–1 (Ans. B) n = 1 energy level would result in the emission
Sol. The expression of Ionization energy is - of X-ray with  = 3.0 × 10–8 m. Which
E = RZ2 hc hydrogen spectrum like species does this atomic
For Li+2 ion, Z = 3, hence no. corresponds to –
Sol. E1 for H = – 13.6 eV
E = (1.0974 × 107 m–1) × (9)
× (6.626 × 10–34 J.S.) × (3 × 108 ms–1)  E2 for H = ( – 13.6/22)= – 13.6/4 = – 3.4 eV
= 1.964 × 10–17 J  E2 – E1 = – 3.4 – ( – 13.6) = + 10.2 eV
For one mole of ions, we have Also for transition of H like atom ;
E’ = NA . E  = 3.0 × 10– 8 m

= (6.023 x 1023 mol–1) (1.964 x 10–17 J) = RH . Z2

7 –1
= 1.118 x 10 J mol
ATOMIC STRUCTURE 31
 n × 31.445 × 10– 21 = 35000
= 1.09 × 107 × Z2 ×
n= = 1113 × 1021
 Z2 = 4 and Z = 2

Ex.11 The shortest wave length in H spectrum of Ex.14 Calculate the number of photons emitted in 10
Lyman series when RH = 109678 cm–1 is - hours by a 60 W sodium lamp
(A) 1215.67 Å (B) 911.7 Å (of photon = 5893 Å) -
(C) 1002.7 Å (D) 1127.30 Å (Ans B) Sol. Energy emitted by sodium lamp in one sec.
Sol. For Lyman series n1 = 1 = Watt. × sec= 60 × 1 J
For shortest ‘’ of Lyman sereis the energy
differnece in two levels showing transition Energy of photon emitted =
should be maximum (i.e. n2 = ).
=
= RH
= 3.37 × 10– 19 J
= 109678  No. of photons emitted per sec. =
  = 911.7 × 10– 8
= 911.7 Å

Ex.12 The energy of an electron in the second and  No. of photons emitted in 10 hours
third Bohr orbits of the hydrogen atom is = 17.8 × 1019 × 10 × 60 × 60
– 5.42 × 10–12 ergs and – 2.41 × 10– 12 erg = 6.41 × 1024
respectively. Calculate the wavelength of the
emitted radiation when the electron drops from Ex.15 Calculate the wavelength of a moving electron
third to second orbit - having 4.55 × 10– 25 J of kinetic energy -
Sol. Here, h = 6.62 × 10– 27 erg Sol. Kinetic energy = (½mu2) = 4.55 × 10–25 J
E3 = – 2.41 × 10– 12 erg
E2 = – 5.42 × 10– 12 erg  u2 =
E = E3 – E2
 u = 103 m sec–1
– 12 – 12
= – 2.41 × 10 + 5.42 × 10
Now we know that, E = hv  = =

v= = = = 7.27 × 10– 7 meter

Ex.16 The minimum energy required to overcome the

 = . attractive forces electron and surface of Ag
metal is 7.52 × 10– 19 J. What will be the
 = 6.6 × 10–5 cm
maximum K.E. of electron ejected out from Ag
Since, 1Å = 10–8 cm
which is being exposed to U.V. light of  = 360 Å
 = 6.6 × 103 Å
(A) 36.38 × 10– 19 Joule
Ex.13 Find the number of quanta of radiations of (B) 6.92 × 10–19 Joule
frequency 4.75 × 1013 sec–1, required to melt (C) 57.68 × 10– 19 Joule
100 g of ice. The energy required to melt 1 g of (D) 67.68 × 10– 19 Joule (Ans. B)
ice is 350 J –
Sol. E = nhv Sol. Energy absorbed =
= n × 6.62 × 10– 34 J sec × 4.75 × 1013 sec–1
= n × 31.445 × 10– 21 J =
Energy required to melt 100 g ice = 350 J × 100
= 35000 J = 5.52 × 10–11 erg
ATOMIC STRUCTURE 32
 = 5.52 × 10–18 Joule when n = 6 then, the no. of spectral lines
–19 –19
= ( 7.52 × 10 ) – ( . 552 × 10 )
= = = 15
–19
= 6.92 × 10 Joule

Ex.20 An electron beam can undergo diffraction by

crystals. Through what potential should a beam
Ex.17 In hydrogen atom , an electron in its normal of electrons be accelerated so that its
state absorbs two times of the energy as if wavelength becomes equal to 1.54 Å -
requires to escape (13.6 eV) from the atom. The Sol. We know that
wave length of the emitted electron will be – mu2 = eV
(A) 1.34 × 10–10 m (B) 2.34 × 10–10 m
(C) 3.34 × 10–10 m (D) 4.44 × 10–10 m
and  = or u = or u2 =
(Ans C)
Sol. Energy absorbed by an atom
= 2 × 13.6 = 27.2 eV  m× = eV
Energy consumed in escape
= 13.6 eV
or V= m× = ×
Energy converted into K.E.
= 13.6 × 1.6 × 10–19 J Substituting the values, we get

v= = V = ×

= 2.18 × 106 ms–1

 = =
= 63.3 volt

Ex.21 What designation will you assign to an orbital

having following quantum number –
= 3.34 × 10–10 m (a) n = 3, l = 1, m = –1
(b) n = 4, l = 2, m = +2
Ex.18 Show that the wavelength of a 150 g rubber ball
(c) n = 5, l = 0, m=0
moving with a velocity 50 m sec–1 is short (d) n = 2, l = 1, m=0
enough to be observed - Sol. (a) Since l = 1 corresponds to p-orbital and m
Sol.  = = –1 shows orientation either in x or y axis, thus
this orbital refers to 3px or 3py
Given u = 50 m sec–1
(b) 4dxy or
= 50 × 102 cm sec– ; m = 150 g
(c) 5s
 = = 8.83 × 10 – 33
cm (d) 2pz

The wavelength is much smaller than the  of Ex.22 How many electrons in a given atom can have
visible region and thus it will not be visible. the following quantum numbers –
(a) n = 4, l = 1
Ex.19 If an electron is present in n = 6 level. How (b) n = 2, l = 1, m = – 1, s = + ½
many spectral lines would be observed in case (c) n = 3
of H atom – (d) n = 4, l = 2, m = 0
(A) 10 (B) 15 (C) 20 (D) 25 Sol. (a) l = 1 refers to p - subshell which has three
(Ans B) orbitals (px, py and pz) each having two
Sol. The no. of spectral lines is given by electrons. Therefore, total number of electrons
are 6.
ATOMIC STRUCTURE 33
 (b) l = 1 refers to p - subshell, m = – 1 refers to p x ( , ), ( , ), ( , ,)
or py orbital whereas, s = +½ indicate for only 1
Isobars : ( , ),( , )
electron.
(c) For n = 3, l = 0, 1, 2 Isotones : ( , ), ( , )
Total number of electrons for any energy level
is given by
Ex.26 Atomic radius is the order of 10 – 8
cm. and
2n2 i.e. 2 × 32 = 18 electrons
nuclear radius is the order of 10–13 cm.
(d) l = 2 means d-subshell and m = 0 refer to dz2 orbital
Calculate what fraction of atom is occupied by
Number of electrons are 2.
nucleus -
Ex.23 Which of the following set of quantum numbers
Sol. Volume of nucleus = (4/3) r3
are not permitted -
(a) n = 3, l = 2, m = – 1, s=0 = (4/3)  × (10–13)3 cm3
(b) n = 2, l = 2, m = +1, s=–½ volume of atom=4/3 r3 = (4/3) × (10– 8)3 cm3
(c) n = 3, l = 2. m = – 2, s=+½
Sol. (a) This set of quantum number is not  = = 10–15
permitted as value of ‘s’ cannot be zero.
(b) This set of quantum number is not or Vnucleus = 10– 15
× Vatom
permitted as the value of ‘l ’ cannot be
equal to ‘n’. Ex.27 Nitrogen atom has Atomic number 7 & oxygen
(c) This set of quantum number is permitted. has Atomic number 8. Calculate the total
number of electrons in nitrate ion -
Ex.24 Naturally occuring boron consists of two
isotops whose atomic weights are 10 and 11 Sol. No. of electrons in NO3–
The atomic weight of natural boron is 10.8 = (Electrons in N) + (3 × electrons in O)
Calculate the percentage of each isotope in + [1(due to negative charge)]
natural boron- = 7 + 3 × 8 + 1 = 32
Sol. Let the percentage of isotope with atomic wt.
10 = x Ex.28 Calculate the velocity of an electron revolving
 Percentage of isotope with atomic wt. in the second orbit of a hydrogen atom from the
11 = 100 – x given data.
For hydrogen ; Z = 1, n = 1.
Average atomic wt. =
v1 =
or Average atomic wt.

= =

= 2.19 × 108 cm/s.

10.81 = x = 20
Sol. v1 = 2.19 × 108 cm/s
 % of isotope with atomic wt. 10 = 20
We have, vn = .
% of isotope with atomic wt. 11 = 100 - x = 80

Ex.25 From the following list of atoms, choose the  v2 =

isotopes, isobars and isotones - = 1.09 × 108 cm/s.
, , , , , , , Ex.29 The uncertainty in the momentum of a particle
, is 2.5 × 10–16 g cm s–1. With what accuracy can
its position be determined?
Sol. Isotopes :
(h = 6.625 × 10–27 erg. s, i.e., g cm2 s–1)
ATOMIC STRUCTURE 34
Sol. x. p = = = 4.417 × 10–

19
or x = × J.
 KE of one I2 molecule
= 4.417 × 10–19 – 3.984 × 10–19 J
= = 4.33 × 10–20 J

= 2.11 × 10–12 cm. KE of one I atom =

Ex.30 The uncertainties in the position and velocity of
a particle are 10–10 m and 5.27 × 10–24 m s–1 = 2.165 × 10–20 J.
respectively. Calculate the mass of the particle.
(h = 6.625 × 10–34 J.s) Ex.33 The ionization energy of He+ is 19.6 × 10–18 J
atom–1. Calculate the energy of the first
Sol. We have, x. (m v) = stationary state of Li2+.
Sol. Energy of the first orbit of Li2+
or m= × (EHe+)1 = –Z2He (constant)
(ELi2+)1 = –Z2Li (constant)
=
(ELi2+)1 = (EHe+)1

= 0.10 kg.
= × 19.6 × 10–18 J atom–1
Ex.31 How many photons of light having a
wavelength of 4000 Å are necessary to provide = 44.1 × 10–18 J atom–1
1 J of energy ?
(h = 6.63 × 10–34 J . s, c = 3 × 108 m/s) Ex.34 Calculate the wavelength and energy of the
radiation emitted for the electronic transition
Sol. Energy of a photon = hv = from infinity () to stationary state first of the
hydrogen atom. (RH = 1.09678 × 107 m–1,
= h = 6.6256 × 10–34 J-s)
Sol. n1 = 1, n2 = 
= 4.97 × 10–19 J.
 number of photons required = RH
= = 2.01 × 1018.
= 1.09678 × 107 .
Ex.32 The iodine molecule dissociates into atoms after
absorbing light of 4500 Å if one quantum of  = 9.11 × 10–8 m
radiation is absorbed by each molecule. E = hv = h × c/
Calculate the kinetic energy of iodine atoms. (C = 3 × 108 m sec–1)
(Bond energy of I2 = 240 kJ mol–1)
Sol. Bond energy per molecule of I2 =

= = 3.984 × 10–19 J. = 2.18 × 10–21 kJ.

Ex.35 Calculate the momentum of a moving particle
Energy absorbed =
which has a de-Broglie wave length of 2 Å.
Sol. According to de-Broglie equation

=

ATOMIC STRUCTURE 35
 n=2
p=
As there are two unpaired electrons so Ni is in
Ni2+ state. Hence its configuration is written as
= 28Ni
2+
: [Ar]3d8
Ex.38 A bulb emits light of  4500 Å. The bulb is
= 3.31 × 10–24 Kg ms–1
rated as 150 watt and 8 per cent of the energy is
Ex.36 A cricket ball weighing 100 g is to be located emitted as light. How many photons are emitted
with 0.1 Å. What is the uncertainty in its by the bulb per second ?
velocity ? Sol. Energy of one photon =
Sol. x . m v =
=
x = Location of ball = 0.1 Å = 0.1 × 10–10 m
m = Mass of ball = 100 g = 0.1 kg = 4.42 × 10–19 J
v = Uncertainty in velocity
Energy emitted by the bulb = 150 × J
h = 6.626 × 10–34 Js

0.1 × 10–10 × 0.1 × v = n × 4.42 × 10–19 = 150 ×

v = 0.527 × 10–22 ms–1 n = 27.2 × 1018

Ex.37 A compound of Nickel has a magnetic moment
of 2.79 BM. Write the electronic configuration
of the nickel ion in this compound.
Sol. As µ =
2.79 =
On solving,

ATOMIC STRUCTURE 36
 LEVEL # 1
(C) –0.85 eV (D) –1.70 eV
Q.8 The frequency of line spectrum of sodium is
5.09 x 1014 sec–1. Its wave length (in nm) will
Q.1 The study of cathode rays (i.e. electronic be - [c = 3 × 108 m/sec]-
discharge through gases) shows that - (A) 510 nm (B) 420 nm
(A) Alpha particles are heavier than protons
(C) 589 nm (D) 622 nm
(B) All forms of matter contain electrons
Q.9 The spectrum of He-atom may be considered
(C) All nuclei contain protons similar to the spectrum of -
(D) e/m is constant (A) H (B) Li+ (C) Na (D) He+
Q.2 Proton is - Q.10 Supposing the energy of fourth shell for
hydrogen atom is - 50 a.u. (arbitrary unit). What
(A) Nucleus of deuterium
would be its ionization potential -
(B) Ionised hydrogen molecule (A) 50 (B) 800 (C) 15.4 (D) 20.8
(C) Ionised hydrogen atom Q.11 Supposing the ionization energy of hydrogen
(D) An -particle atom is 640 eV. Point out the main shell having
energy equal to – 40 eV -
Q.3 Which is not deflected by magnetic field -
(A) n = 2 (B) n = 3
(A) Neutron (B) Electron and Neutron
(C) n = 4 (D) n = 5
Q.12 A 1-kW radio transmitter operates at a
(C) Proton (D) Electron frequency of 880 Hz. How many photons per
Q.4 According to Dalton’s atomic theory, an atom second does it emit -
can – (A) 1.71 x 1021 (B) 1.71 x 1033
(C) 6.02 x 1023 (D) 2.85 x 1026
(A) Be created
Q.13 On Bohr’s stationary orbits -
(B) Be destroyed
(A) Electrons do not move
(C) Neither be created nor destroyed (B) Electrons move emitting radiations
(D) None (C) Energy of the electron remains constant
Q.5 Rutherford’s experiment on scattering of alpha (D) Angular momentum of the electron is h/2
particles showed for the first time that atom has- Q.14 The value of Bohr radius of hydrogen atom is -
(A) Electrons (B) Protons (A) 0.529x 10–7cm (B) 0.529x 10-8cm
(C) Nucleus (D) Neutrons (C) 0.529x 10-9cm (D) 0.529x 10–10 cm
Q.15 On the basis of Bohr’s model, the radius of the
Q.6  - particles are represented by –
3rd orbit is -
(A) Lithium atoms (B) Helium nuclei (A) Equal to the radius of first orbit
(C) Hydrogen nucleus (D) None of these (B)Three times the radius of first orbit
(C) Five times the radius of first orbit
(D) Nine time the radius of first orbit
Q.16 The correct expression derived for the energy of
Q.7 The energy of electron in first Bohr’s orbit of an electron in the nth energy level is for H-atom-
H-atom is –13.6 eV. What will be its potential
energy in n = 4th orbit - (A) En = (B) En = –
(A) – 13.6 eV (B) –3.4 eV
ATOMIC STRUCTURE 37
 The order of the energies would be –
(C) En = – (D) En= – (A) E1 > E2 > E3 (B) E3 > E2 > E1
(C) E1 = E2 = E3 (D) None of these
Q.17 Ionization energy for hydrogen atom in ergs,
Joules and eV respectively is -
(A) 21.8 x 10–12 , 218 x 10–20 , 13.6
Q.25 The wave number of the first line of Balmer
(B) 13.6 x 218 x 10–20, 21.8 x 10–13
series of hydrogen is 15200 cm–1. The wave
(C) 21.8 x 10–20, 13.6 , 21.8 x 10–13
number of the first Balmer line of Li2+ ion is-
(D) 21.8 x 10–13, 13.6, 21.8 x 10–20
(A) 15200cm–1 (B) 60800 cm–1
Q.18 The velocity of an electron in the third orbit of
(C) 76000 cm–1 (D) 136800 cm–1
hydrogen atom -
Q.26 The wavelength of the third line of the Balmer
(A) 7.28 x107 cm sec–1 (B) 7.08 x 107 cm sec–1
series for a hydrogen atom is -
(C) 7.38 x 107cm sec–1 (D) 7.48 x107cm sec–1
Q.19 The ionization energy of a hydrogen atom is (A) (B)
13.6eV. The energy of the third-lowest
electronic level in doubly ionized lithium ion (C) (D)
(Z = 3) is -
(A) –28.7 eV (B) –54.4 eV Q.27 Wave number of a spectral line for a given
(C) –122.4 eV (D) –13.6 eV transition is x cm–1 for He+ , then its value for
Q.20 Difference between Cl atom and Cl– ion is of : Be3+ for the same transition is -
(A) Proton (A) 4x cm–1 (B) x cm–1
(B) Neutron (C) x/4 cm–1 (D) 2x cm–1
(C) Electron Q.28 A photon was absorbed by a hydrogen atom in
(D) Proton and electron its ground state and the electron was promoted
Q.21 For ionising an excited hydrogen atom, the to the fifth orbit. When the excited atom
energy required in eV will be - returned to its ground state, visible and other
(A) 3.4 or less (B) More than 13.6 quanta were emitted. Other quanta are -
(C) Little less than 13.6 (D) 13.6 (A) 2  1 (B) 5  2
(C) 3  1 (D) 4  1
Q.22 A gas absorbs a photon of 300 nm and then re-
Q.29 Wave-length of the first line of Paschen Series
emits two photons. One photon has a
wavelength 600 nm. The wavelength of second hydrogen spectrum is -
photon is -
(A) 300 nm (B) 400 nm (A) 18761(Å) (B) 2854 (Å)
(C) 500 nm (D) 600 nm (C) 3452 (Å) (D) 6243 (Å)
Q.30 Electronic transition in He+ ion takes from n2 to
Q.23 The energy of a photon of radiation having
n1 shell such that :
wavelength 300 nm is -
2n2 + 3n1 = 18 ….(i)
(A) 6.63 × 10–29 J (B) 6.63 × 10–19 J
2n2 – 3n1 = 6
(C) 6.63 × 10–28 J (D) 6.63 × 10–17 J
Then what will be the total number of photons
Q.24 For H– atom, the energy required for the emitted when electrons transit to n1 shell ?
removal of electron from various sub-shells is (A) 21 (B) 15
given as under– (C) 20 (D) 10

Q.31 If the shortest wavelength in Lyman series of H

atom is x, then longest wavelength in Balmer
series of He+ is -
ATOMIC STRUCTURE 38
 (A) (B) (C) (D) Q.38 Maximum number of electrons in a subshell is
given by -
(A) (2 + 1) (B) 2(2 +1)
Q.32 Which of the following expressions represents (C) (2 +1) 2
(D) 2(2 + 1)2
the spectrum of Balmer series(If n is the
principal quantum number of higher energy Q.39 The magnetic quantum number for valence
level) in Hydrogen atom - electron of sodium atom is -
(A) 3 (B) 2
(A) (C) 1 (D) Zero
Q.40 Which one of the following represents an
impossible arrangement –
(B) n  m s
(A) 3 2 –2 1/2
(C) (B) 4 0 0 1/2
(C) 3 2 –3 1/2
(D) 5 3 0 1/2
(D) Q.41 The set of quantum number for the 19th
electron in chromium is -
(A) n=4, =0, m=0, s =+1/2 or -1/2
(B) n=3,  =2, m=1, s=+1/2 or -1/2
(C) n=3,  =2, m= -1, s=+1/2 or -1/2
Q.33 The maximum number of electrons in a
(D) n=4,  =1, m=0, s=+1/2 or -1/2
principal shell is - Q.42 The electronic configuration together with the
2 quantum number of last electron for lithium is -
(A) 2n (B) 2n (C) 2 (D) n

Q.34 Which of the following statements concerning (A) 1s22s1 2, 0, 0 +

the four quantum numbers is false -
(A) n gives idea of the size of an orbital (B) 1s22s1 2, 0, 0 + or –
(B)  gives the shape of an orbital
(C) m gives the energy of the electron in the
(C) 1s22s02p1 2, 1, 0 ±
orbital
(D) s gives the direction of spin of the
electron in an orbital (D) 2s22s1 2,1, 0 ±

Q.35 How many electrons can fit into the orbitals that Q.43 Four sets of values of quantum numbers
comprise the 3rd quantum shell n = 3 - (n, , m and s) are given below. Which set does
(A) 2 (B) 8 not provide a permissible solution of the wave
equation -
(C) 18 (D) 32
(A) 3, 2, –2, (B) 3, 3, 1, –
Q.36 The shape of the orbital is given by -
(A) Spin quantum number (C) 3, 2, 1, (D) 3, 1, 1,
(B) Magnetic quantum number
(C) Azimuthal quantum number

(D) Principal quantum number

Q.37 The set of quantum numbers not applicable for Q.44 Which of the following sets of quantum
an electron in an atom is – numbers is correct for an electron in 4 f-orbital?
(A) n = 1,  = 1, m = 1, s = + 1/2
(B) n = 1,  = 0, m = 0, s = + 1/2 (A) n = 4, l = 3, m = +4, s = +
(C) n = 1,  = 0, m = 0, s = – 1/2
(D) n = 2,  = 0, m = 0, s = + 1/2
ATOMIC STRUCTURE 39
 (B) n = 4, l = 4, m = –4, s = –
Q.53
(C) n = 4, l = 3, m = +1, s = +
The above configuration is not correct as it
(D) n = 3, l = 2, m = –2, s = + violates -
(A) Only Hund’s rule
(B) Only Pauli’s exclusion principle
Q.45 In which of the following pairs is the (C) (n + ) rule
probability of finding the electron in xy-plane (D) (Hund + Pauli) rule
zero for both orbitals ?
(A) (B) Q.54 Which of the following elements is represented
by the electronic configuration -
(C) 4dzx, 3pz (D) All of these
Q.46 For 4py orbital : There are -
nodal plane = ........ and azimuthal quantum
number  =
(A) 1, 0 (B) 0, 1 (C) 1, 1 (D) 2, 1
Q.47 The maximum probability of finding electron in (A) Nitrogen (B) Fluorine
the dxy orbital is -
(C) Oxygen (D) Neon
(A) Along the x axis
(B) Along the y axis Q.55 The electronic configurations of 24Cr and 29Cu
(C) At an angle of 45º from the x and y axis are abnormal -
(D) At an angle of 90º from the x and y axis (A) Due to extra stability of exactly half filled
and exactly fully filled sub shells
(B) Because they belong to d-block
Q.48 An electron has a spin quantum number
+ 1/2 and a magnetic quantum number –1. It (C) Both the above
cannot be present in - (D) None of the above
(A) d-Orbital (B) f-Orbital Q.56 The electronic configuration of chromium
(C) s-Orbital (D) p-Orbital (Z = 24) is -
Q.49 If the electronic structure of oxygen atom is
(A) [Ne]3s23p63d44s2 (B) [Ne] 3s23p63d54s1
2 2
written as 1s , 2s it would violate- (C) [Ne]3s23p63d14s2 (D) [Ne] 3s23p64s24p4
(A) Hund’s rule Q.57 The number of d-electrons in Fe2+ (At. no. 26) is
not equal to that of the –-
(B) Paulis exclusion principle
(A) p-Electrons in Ne (At. No. 10)
(C) Both Hund’s and Pauli’s principles
(D) None of these (B) s-Electrons in Mg (At No. 12)
Q.50 The energy of an electron of 2py orbital is - (C) d-Electrons in Fe atom
(A) Greater than 2px orbital (D) p-Electrons in Cl¯ ion (At. No. 17)

(B) Less than 2pz orbital

(C) Equal to 2s orbital
Q.58 In an electron microscope, electrons are
(D) Same as that of 2px and 2pz orbitals accelerated to great velocities. Calculate the
Q.51 The number of unpaired electrons in carbon wavelength of an electron travelling with a
atom is -
velocity of 7.0 megameters per second . The
(A) 2 (B) 4 (C) 1 (D) 3
Q.52 When 4 d orbital is complete, the newly mass of an electron is 9.1×10-28 g -
entering electrons goes in to - (A) 1.0 × 10–13m (B) 1.0 × 10–7m
(A) 5f (B) 5s
(C) 5p (D) 6d Orbital (C) 1.0 m (D) 1.0 × 10–10m

ATOMIC STRUCTURE 40
Q.59 A 200g cricket ball is thrown with a speed of (A) Zero (B)
3.0 x 103 cm sec–1. What will be its de Broglie’s (C) h (D) Infinite
–27 2 –1
wavelength - [h = 6.6 x 10 g cm sec ]
(A) 1.1 x 10 –32
cm (B) 2.2 x 10–32 cm Q.64 Which of the following is the most correct
expression for Heisenberg's uncertainty
(C) 0.55 x 10–32 cm (D) 11.0 x 10–32 cm
principle
Q.60 Which is the de-Broglie equation -
(A) h = p (B) h = p–1 (A) x. p = (B) x. p 
–1
(C) h = p (D) h = p + 
(C) x. p  (D) x. v 
Q.61 Which of the following has the largest de
Broglie wavelength given that all have equal Q.65 The Heisenberg uncertainty principle can be
velocity - applied to -
(A) CO2 molecule (B) NH3 molecule (A) A cricket ball (B) A foot ball
(C) Electron (D) Proton (C) A jet aeroplane (D) An electron

Q.62 A ball has a mass of 0.1 kg its velocity is Q.66 Velocity of helium atom at 300 K is 2.40 x 10 2
40 m/s, find out de Broglie wave length - meter per sec. What is its wave length -
(A) 1.66 x 10–34m (B) 2 x 10–34 m (mass number of helium is 4)
(C) 3 x 10–34 m (D) 4 × 10–34 m (A) 0.416 nm (B) 0.83 nm
(C) 803 Å (D) 8000Å
Q.63 If the uncertainty of position for an electron is
zero, what is the uncertainty of the momentum-

ATOMIC STRUCTURE 41
 LEVEL # 2
Q.1 The wave character of electron was to be half of its original value whereas that of
experimentally verified by - electron is assumed to be twice of this original
(A) de - Broglie (B) A. Einstein value. The atomic mass of 6C12 will be -
(C) Germer (D) Schrodinger (A) Twice
Q.2 Which of the following is not possible ? (B) 75% less
(A) n = 2, l = 1, m = 0 (C) 25% less
(B) n = 2, l = 0, m = –1 (D) One-half of its original value
(C) n = 3, l = 0, m = 0 Q.9 The energy difference between two electronic
(D) n = 3, l = 1, m = –1 states is 46 .12 kcal /mole. What will be the
Q.3 What is the maximum number of electrons in an frequency of the light emitted when an electron
atom that can have the quantum numbers drops from the higher to the lower energy state
n = 4, m = +1 ?
(Planck' constant = 9.52 x 10-14 kcal sec mole -1)
(A) 4 (B) 15
(A) 4.84 x 10 15 cycles sec -1
(C) 3 (D) 6
(B) 4.84 x 10 -5 cycles sec-1
Q.4 Arrange the orbitals of H-atom in the increasing
order of their energy - (C) 4.84x 10-12 cycles sec-1
3px, 2s, 4dxy , 3s, 4pz , 3py , 4s (D) 4.84 x 10 14 cycles sec-1
Q.10 If the kinetic energy of an electron is increased
(A) 2s < 3s = 3px = 3py < 4s = 4pz = 4dxy
4 times, the wavelength of the de Broglie wave
(B) 2s < 3s < 3px = 3py < 4s = 4pz = 4dxy associated with it would become :
(C) 2s < 3s < 3px = 3py < 4s = 4pz = 4dxy (A) 4 times
(B) 2 times
(D) 2s < 3s < 3px = 3py < 4s < 4pz < 4dxy
(C) times
Q.5 Electron, Proton and Neutron were respectively
discovered by -
(D) times
(A) James Chadwick, John Dalton, J.J.
Thomson Q.11 Multiple of fine structure of spectral lines is
(B) J.J. Thomson, Goldstein, John Dalton due to-
(C) J.J. Thomson, William Crookes, Goldstein (A) Presence of main energy levels
(D) J.J. thomson, Goldstein , James Chadwick (B) Presence of sub- levels
Q.6 If the I.P. of Li+2 is 122.4 eV. Find out 6 th I.P. (C) Presence of electronic configuration
of carbon - (D) Is not a characteristics of the atom.
(A) 122.4 × 4eV (B) 122.4 × 2eV Q.12 The quantum number not obtained from the
(C) 122.4 × 3eV (D) 122.4 × 5eV Schrodinger’s wave equation is -
Q.7 If W is the mass number and N is the atomic (A) n
number of an element, the number of - (B) 
(A) Electrons = W – N (B) Neutrons = W – N (C) m
(C) Protons = W – N (D) Electrons = W (D) s
Q.8 It is known that atoms contain protons, neutrons Q.13 Wave mechanical model of the atom depends
and electrons. If the mass of neutron is assumed upon-
ATOMIC STRUCTURE 42
 (A) de-Broglie concept of dual nature of (A) 60 (B) 32 (C) 64 (D) 50
electron Q.23 If the value of (n +  ) is not > 3, then the
(B) Heisenberg uncertainty principle maximum number of electrons in all the orbitals
(C) Schrodinger uncertainty principle would be -
(D) All (A) 12 (B) 10 (C) 2 (D) 6
Q.14 The correct Schrodinger's wave equation for an
electron with total energy E and potential Q.24 It is not possible to explain the Pauli's exclusion
energy V is given by - principle with the help of this atom -
(A) B (B) Be
(A) + + + (E–V)  = 0 (C) C (D) H
Q.25 Uncertainty in position and momentum are
equal. Uncertainty in velocity is -
(B) + + + (E–V)  = 0
(A) (B)
(C) + + + (E–V)  =
(C) Both (D)
0
(D) None of the above. Q.26 For any H like system, the ratio of velocities of
Q.15 Calculate total no. of e– having m = 0 in Cr I, II & III orbit i.e. V1 : V2 : V3 will be -
atom - (A) 1 : 2 : 3 (B) 1 : 1/2 : 1/3
(A) 12 (B) 13 (C) 5 (D) 24 (C) 3 : 2 : 1 (D) 1 : 1 : 1
Q.16 Which orbital is dumb-bell shaped - Q.27 How fast is an electron moving if it has a
(A) s-Orbital (B) p-Orbital wavelength equal to the distance it travels in
(C) d-Orbital (D) f-Orbital one second -
Q.17 Which of the following subshell can (A) (B)
accommodate as many as 10 electrons -
(A) 2d (B) 3d
(C) (D)
(C) 3dxy (D) 3dz2
Q.18 "No two electrons in an atom can have the same
Q.28 Which of the following is isotone of
set of four quantum numbers. "This principle
was enunciated by - (A) (B)
(A) Heisenberg (B) Pauli (C) (D)
(C) Maxwell (D) de Broglie.
Q.29 The correct statement(s) about Bohr’s orbits of
Q.19 How many spherical nodes are present in a 4s hydrogen atom is/are -
orbital in hydrogen atom -
(A) 0 (B) 1 (C) 2 (D) 3 (A) r =
Q.20 Minimum core charge is shown by the atom -
(A) O (B) Na (B) K.E. of the electron = –1/2 (P. E. of the
(C) N (D) Mg electron)
Q.21 I.P. of hydrogen atom is equal to 13.6 eV. What
is the energy required for the process : (C) Angular momentum (L) = n

He+ + energy — He+2 + e– (D) All the above

(A) 2 × 13.6 eV (B) 1 × 13.6 eV
(C) 4 × 13.6 eV (D) None of these Q.30 In centre-symmetrical system, the orbital
Q.22 If elements with principal quantum number angular momentum, a measure of the
n > 4 is not allowed in nature, the number of momentum of a particle travelling around the
possible elements would be - nucleus, is quantised. Its magnitude is -
ATOMIC STRUCTURE 43
 (Atomic numbers : Cr = 24, Fe = 26, Co = 27,
(A) (B) Ni = 28)
The correct sequence of the increasing order of
(C) (D) the number of unpaired electrons in these ions
is-
(A) 1, 2, 3, 4 (B) 4, 2, 3, 1
Q.31 Each orbital has a nodal plane. Which of the (C) 1, 3, 2, 4 (D) 3, 4, 2, 1
following statements about nodal planes are not Q.39 What are the values of the orbital angular
true - momentum of an electron in the orbitals 1s, 3s,
(A) A plane on which there is zero probability 3d and 2p -
that the electron will be found (A) 0, 0, ,  (B) 1, 1, ,
(B) A plane on which there is maximum
(C) 0, 1, , (D) 0, 0, ,
probability that the electron will be found
(C) Both
Q.40 In an atom two electrons move around the
(D) None nucleus in circular orbits of radii R and 4R. The
Q.32 n and l values of an orbital ‘A’ are 3 and 2, of ratio of the time taken by them to complete one
another orbital ‘B’ are 5 and 0. The energy of = revolution -
(A) B is more than A (A) 1 : 4 (B) 4 : 1
(B) A is more than B (C) 1 : 8 (D) 8 : 7
(C) A and B are of same energy Q.41 A beam of electrons is accelerated by a potential
difference of 10000 volts. The wavelength of
(D) None
the wave associated with it will be -
Q.33 If Hund’s rule is followed, magnetic moment of
(A) 0.0123 Å (B) 1.23 Å
Fe2+, Mn+ and Cr all having 24 electrons will be (C) 0.123 Å (D) None of these
in order -
Q.42 If the number of electrons in p-orbital are two,
(A) Fe2+ < Mn+ < Cr (B) Fe2+ < Cr = Mn+
then which one of the following is in
(C) Fe2+ = Mn+ < Cr (D) Mn2+ =Cr <Fe2+ accordance with Hund’s rule -
Q.34 The ionisation potential of the hydrogen atom is
13.6 eV. The energy needed to ionise a (A) (B)
hydrogen atom which is in its second excited
state is about : (C) (D)
(A) 13.6 eV (B) 10.2 eV Q.43 If there are six energy levels in H–atom then the
(C) 3.4 eV (D) 1.5 eV number of lines in its emission spectrum in ultra
Q.35 Magnetic moments of V(Z = 23), Cr(Z = 24), voilet region will be -
Mn(Z = 25) are x, y, z. Hence -
(A) x = y = z (B) x < y < z (A) 6 (B) 5 (C) 4 (D) 3
(C) x < z < y (D) z < y < x
Q.44 Magnetic moment of X3+ ion of 3d series is
Q.36 The uncertainty in the position of an electron
BM. What is atomic number of X3+ ?
moving with a velocity of 1 × 10 4 cm s–1
(accurate up to 0.011%) will be : (A) 25 (B) 26 (C) 27 (D) 28
(A) 1.92 cm (B) 7.68 cm
(C) 0.528 cm (D) 3.8 cm Q.45 An electron is moving with the velocity equal to
Q.37 The ratio of (E2 – E1) to (E4 – E3) for the 10% of the velocity of light. Its de-Broglie wave
length will be -
hydrogen atom is approximately equal to -
(A) 10 (B) 15 (A) 2.4 × 10-12cm (B) 2.4 × 10-18cm
(C) 17 (D) 12
Q.38 Consider the following ions - (C) 2.4 × 10–9cm (D) None of these
(1) Ni2+ (2) Co2+ (3) Cr2+ (4) Fe3+

ATOMIC STRUCTURE 44
Q.46 Correct set of four quantum numbers for the (D) All the four quantum numbers of two
valence (outer most) electron of rubidium electrons in an atom cannot be equal.
(Z = 37) is -
Q.54 Which element is represented by the following
electronic configuration -
(A) 5,0,0, + (B) 5,1,0, +

(C) 5,1,1, + (D) 5,0,0, –

Q.47 Ratio of time period of electron in first and (A) Nitrogen (B) Oxygen
second orbit of H-atom would be - (C) Fluorine (D) Neon
Q.55 When an electron jumps from L to K shell -
(A) 1 : 18 (B) 1 : 8 (C) 1 : 2 (D) 2 : 1
(A) Energy is absorbed
Q.48 If x is the velocity of an electron in first Bohr’s (B) Energy is released
orbit. What would be the velocity of the (C) Energy is neither absorbed nor released
electron in third Bohr’s orbit - (D) Energy is sometimes absorbed and some
times released
(A) (B) (C) 3x (D) 9 x Q.56 The orbital diagram in which ‘Aufbau principle’
is violated is -
Q.49 The following graph between 2 probability
density and distance from the nucleus represents- (A)

(B)

(C)

(D)
(A) 2s (B) 3s (C) 1s (D) 2p Q.57 d6 configuration will result in total spin of -
Q.50 The wave length of the last line of Paschen (A) 3/2 (B) ½ (C) 2 (D) 1
series would be - Q.58 Bohr’s model can explain -
(A) 9540 Å (B) 8204 Å (C) 3650 Å (D) 912 Å
(A) The spectrum of only hydrogen atom
Q.51 The wavelength of X-ray is 10-6 cm. Its
(B) The spectrum of the atoms of all the
frequency in Giga Hertz (GHz) will be (Hint : 1
elements
Giga = 109)
(C) The spectrum of only sodium atom
(A) 3 × 107 (B) 3 × 109
(D) The spectrum of atomic or ionic species
10
(C) 3 × 10 (D) 3 × 108
having one electron.
Q.52 Which electronic level would allow the
Q.59 The mass number of dipositive Zn ion is 70.
hydrogen atom to absorb a photon but not to
The total number of neutrons is -
emit a photon
(A) 3s (B) 2p (C) 2s (D) 1s (A) 34 (B) 40 (C) 36 (D) 38
Q.53 Pauli’s exclusion principle states that - Q.60 The energy required to separate an electron
(A) Nucleus of an atom contains no negative from the level n = 3 of a H-atom is 9.69 × 10 –19
charge Joules. What will be its energy in first excited
(B) Electrons move in circular orbits around the state -

nucleus
(C) Electrons occupy orbitals of lowest energy

ATOMIC STRUCTURE 45
 (A) – 9 × 9.69 × 10–19 J (B) –

J (C) × 9.69 × 10–19 J (D) (C) (D)

None of these
Q.61 When beryllium is bombarded with alpha
Q.66 The number of elliptical orbits excluding
particles (Chadwick’s experiment) extremely
circular orbits in the N-shell of an atom is -
penetrating radiations which can not be
(A) 3 (B) 4 (C) 2 (D) 1
deflected by electrical or magnetic field are
Q.67 A compound of vanadium has a magnetic
given out. These are -
moment 1.73 B. M. The electronic
(A) A beam of protons
configuration of vanadium ion in the compound
(B) Alpha rays is -
(C) A beam of neutrons
(A) [Ar] 3d2 (B) [Ar] 3d1
(D) A beam of neutrons and protons
(C) [Ar] 3d3 (D) [Ar] 3d04s1
Q.68 How many lines in the spectrum will be
Q.62 The potential energies of first, second and third
+ observed when electrons return from 7th shell to
Bohr’s orbits of He cation are E1, E2 and E3.
2nd shell ?
The correct sequence of these energies is - (A) 13 (B) 14 (C) 15 (D) 16
(A) E1 > E2 > E3 (B) E1 = E2 > E3
Q.69 In Ca atom how many e– contain m = 0
(C) E1 = E2 = E3 (D) E3 > E2 > E1 (A) 12 (B) 8 (C) 10 (D) 18
Q.63 When an electron transit form n = 4 to n = 2, Q.70 In Ne how many e– contain m = –1
then emitted line in spectrum will be : (A) 4 (B) 2 (C) 0 (D) 1
(A) First line of Lyman series
Q.71 What is ratio of time periods (T 1 / T2) in second
(B) Second line of Balmer series
orbit of hydrogen atom to third orbit of He+ ion?
(C) First line of Paschen series
(D) Second line of Paschan series (A) (B) (C) (D)
Q.64 In which of the following orbital diagrams are
both Pauli's exclusion principle and Hund's rule Q.72 The number of electrons in Na, having n+ = 3
violated ? (A) 4 (B) 6 (C) 7 (D) 8
Q.73 Which orbital has 1 nodal plane -
(A)
(A) s (B) p (C) d (D) f
(B) Q.74 How many s electrons are there in Cu+ -
(C) (A) 2 (B) 4 (C) 6 (D) 10
Q.75 If the total energy of an electron in a hydrogen
(D) atom in excited state is –3.4 eV, then the de
Q.65 Which of the following graphs correspond to Broglie wavelength of the electron is -
one node ? (A) 3.3 × 10–10 m (B) 6.6 × 10–10 m
(C) 3.3 × 1010 m (D) 9.3 × 10–12 m
Q.76 The correct set of quantum numbers to the
(A) (B) unpaired electron of fluorine atom -
(A) n = 3,  = 0, m = 0 (B) n = 3,  = 1, m =
1
(C) n = 2,  = 0, m = 0 (D) n = 2,  = 1, m =
1
Q.77 Which of the following statement is correct -
ATOMIC STRUCTURE 46
 (A) Number of angular nodes = n – – 1 Q.85 The uncertainty in velocity of electron having
(B) Number of radial nodes =  uncertainty in its position of 1Å -
(C) Total number of nodes = n – 1 (A) 5.8 × 105 m/s (B) 5.8 × 106 m/s
(D) All (C) 5.8 × 107 m/s (D) 5.8 × 108 m/s
Q.78 The total energy associated per quanta with
light of wavelength 600 nm - Q.86 If ionisation energy of hydrogen atom is
(A) 3.3 × 10–12 erg (B) 3.3 × 10–6 erg 13.6 eV. I.E. of Li+2 will be -
(C) 6.6 × 10–12 erg (D) 6.6 × 10–6 erg (A) 13.6 eV (B) 10.4 eV
Q.79 The number of orbitals in n = 3 are - (C) 40.8 eV (D) 122.4 eV
(A) 1 (B) 3
(C) 5 (D) 9 Q.87 The wavelength of third lyman series of
hydrogen atom is approximately -
Q.80 The number of revolution/sec. made by electron
in 3rd orbit of hydrogen atom - (A) 1 × 10–7 m (B) 1 × 10–8 m
(A) 4.88 × 1014 (B) 2.44 × 1014 (C) 1 × 10–6 m (D) 1 × 10–5 m
(C) 9.9 × 1014 (D) 2.44 × 1012
Q.88 The number of waves made by a Bohr electron
Q.81 Angular and spherical nodes in 3s -
in one complete revolution in its 3rd orbit -
(A) 1, 1 (B) 1, 0
(A) 1 (B) 2
(C) 2, 0 (D) 0, 2
(C) 3 (D) 4

Q.82 The magnetic moment of V4+ ion -

Q.89 If potential energy of an electron in hydrogen
(A) 1.73 (B) 1.41
atom is –x eV, then its kinetic energy will be -
(C) 3.46 (D) 2
(A) x eV (B) –x eV
Q.83 Which orbital represents the following set of (C) 2x eV (D) x/2 eV
quantum numbers n = 3,  = 0, m = 0, s = +1/2 -
(A) 3p (B) 2s
(C) 3s (D) 2p

Q.84 The number of unpaired electrons in Zn+2 -

(A) 0 (B) 1
(C) 2 (D) 3

ATOMIC STRUCTURE 47
 LEVEL # 3
Q.1 An atom has x energy level, then total number quantum numbers  and magnetic quantum
of lines in its spectrum are : numbers ‘m’ are -
(A) 1 + 2 + 3 ...............(x + 1) (A)  m
(B) 1 + 2 + 3 ...............(x2) 0 0
(C) 1 + 2 + 3 ................(x – 1) 1 +1, 0, –1
(D) (x + 1) (x + 2) (x + 4) 2 +2, +1, 0, –1, –2
Q.2 The figure indicates the energy level diagram (B) m
for the origin of six spectral lines in emission 0 1
spectrum (e.g. line no. 5 arises from the 2 +2, 1, –2
transition from level B to X) which of the 3 + 3, + 3, +2, 1, –2, – 3
following spectral lines will not occur in the
absorption spectrum : (C) m
0 0
1 1, 2, 3, 2, 0, 1, 2
2 +3, +2, 1, –2 , –3
(D) m
(A) 1, 2, 3 (B) 3, 2 1 0, 1
(C) 4, 5, 6 (D) 3, 2, 1
Q.3 The graphical representation of energy of e – and 2 0, 1, 2
atomic number is : 3 0, 1, 2, 3
Q.6 An electron, a proton and an alpha particle have
kinetic energies of 16E, 4E and E respectively.
(A) (B) What is the qualitative order of their de Broglie
wavelengths -
(A) e > p =  (B) p =  > e
(C) p < e >  (D)  < e < p
Q.7 How many d-electrons in Cu+ (At. No. = 29)
(C) (D)
can have the spin quantum number ?

(A) 3 (B) 7 (C) 5 (D) 9

Q.4 Which of the following transition neither shows
absorption nor emission of energy in case of Q.8 Compared to the mass of lightest nucleus the
Hydrogen atom : mass of an electron is only :
(A) 3px  3s (B) 3dxy  3dyz
(A) (B) (C) (D)
(C) 3s  3dxy (D) All the above
Q.5 When the value of principal quantum number Q.9 An orbital with  = 0 is Symmetrical about the:
‘n’ is 3, the permitted value of azimuthal
(A) x-axis only (B) y-axis only
ATOMIC STRUCTURE 48
 (C) z-axis only (D) The nucleus (B) Photo electric effect
Q.10 The nucleus of an atom is located at x = y = z = 0. (C) Compton effect
If the probability of finding an s-orbital electron (D) Mechanical effect by cathode rays
in a tiny volume around x = a, y = z = 0 is 1 x Q.18 The nitride ion in lithium nitride is composed
10–5, what is the probability of finding the of:
electron in the same sized volume around x= (A) 7 protons + 10 electrons
z = 0, y = a - (B) 10 protons + 10 electrons
(A) 1 x 10–5 (B) 1 x 10–5 x a (C) 7 protons + 7 protons
(C) 1 x 10–5 x a2 (D) 1 x 10–5 x a–1 (D) 10 protons + 7 electrons
Q.11 Which orbital is represented by wave function 310 Q.19 The emission spectrum of hydrogen is found to
(A) 3 dxy (B) 3 pz (C) 4 s (D) 4 dz2 satisfy the expression for the energy change.
Q.12 Find out ratio of following for photon E (in joules) such that E = 2.18 × 10–18
(max.)Lyman : (max.)Brakett -
(A) 1 : 16 (B) 16 : 1 (C) 1 : 4 (D) 4 : 1 .Where n1=1, 2, 3....and n2 = 2, 3,
Q.13 Let mass of electron is half, mass of proton in
two times and mass of neutron is three fourth of 4... The spectral lines that correspond to
original. The find out new atomic wt. of O 16 Paschan series have :
atom: (A) n1 = 1 and n2 = 2, 3, 4
(A) increases by 37.5% (B) remain constant (B) n1 = 3 and n2 = 4, 5, 6
(C) increases by 12.5% (D) decreases by 25% (C) n1 = 1 and n2 = 3, 4, 5
Q.14 Which of the following is correct radial
(D) n1 = 2 and n2 = 3, 3, 5
probability distribution curve for various
Q.20 The number of neutron in tritium is :
orbitals ?
(A) 1 (B) 2 (C) 3 (D) 0
Q.21 The energy difference between the states n = 2
and n = 3 is E eV, in hydrogen atom. The
(A) (B)
ionisation potential of H atom is -
(A) 3.2 E (B) 5. 6E (C) 7.2 E (D) 13.2 E
Passage :
Orbital is the region in an atom where the
(C) (D) probability of finding the electron is maximum.
It represents three-dimensonal motion of an
electron around the nucleus. Orbitals do not
Q.15 The energies E1 and E2 of two radiations are 25 specify a definite path according to the
eV and 50 eV respectively. The relation uncertainty principle. An orbital is described
between their wavelengths i.e. 1and 2 will with the help of wave function . Whenever
be: an electron is described by a wave function, we
say that an electron occupies that orbital. Since
(A) 1 = 2 (B) 1 = 2
many wave functions are possible for an
(C) 1 = 22 (D) 1 = 42 electron, there are many atomic orbitals in an
Q.16 The momentum of a photon with energy 20 eV atom. Orbitals have different shapes; except
is - s-orbitals, all other orbitals have directional
(A) 10.66 x 10–27 Kg m sec–1 character. Number of spherical nodes in an
(B) 10.55 x 10–27 Kg m sec–1 orbital is equal to (n––1). Orbital angular
(C) 10.60 x 10–27 Kg m sec–1 momentum of an electron is .
(D) 10.80 x 10–27 Kg m sec–1 Q.22 The nodes present in 5p orbital are -
Q.17 Electron corpuscular nature is not connected (A) one planar, five spherical
with - (B) one planar, four spherical
(A) Diffraction phenomenon (C) one planar, three spherical
ATOMIC STRUCTURE 49
 (D) four spherical (D) If Statement - I is false but Statement - II is
Q.23 When an atom is placed in a magnetic field, the true.
possible number of orientations for an orbital of Q.36 Statement I : 2p orbitals do not have any
azimuthal quantum number 3 is - spherical node.
(A) three (B) one (C) five (D) seven Statement II : The number of nodes in
Q.24 Orbital angular momentum of f-electrons is- p-orbitals is given by (n – 2) where n is the
(A) (B) (C) (D) 2 principal quantum number.
Q.25 Which of the following orbitals has/have two Q.37 Statement I : All p-orbitals have only one
nodal planes ? planar node.
(A) dxy (B) dyz Statement II : The number of radial nodes
(C) dxz (D) All of these depends on the principal quantum number only.
Q.38 Statement I : Hydrogen has one electron in its
True or False :
orbit but it produces several spectral lines.
Q.26 The species Na+, Mg2+, Al3+, O2– and F– are Statement II : There are many excited energy
iso-electronic. levels available.
Q.27 The nuclear reaction Q.39 Statement I : The 19th electron in potassium
atom enters into 4 s-orbital and not the
was used by Curie to discover neutron.
3d-orbital.
Q.28 Lyman series of hydrogen spectrum lies in the
Statement II : (n + ) rule is followed for
visible region.
determining the orbital of the lowest energy
state.
Q.29 All the four quantum numbers have been
Q.40 Statement I : The free gaseous Cr atom has six
derived from Schrodinger wave equation.
unpaired electrons.
Q.30 The outer electronic configuration of chromium
Statement II : Half-filled s-orbital has greater
atom is 3d44s2.
stability.
Q.31 The electron density in xy plane of Q.41 Statement I : The electronic configuration of
orbital is zero. the nitrogen atom is represented as
Q.32 All the atomic orbitals are directional in nature.
Q.33 The designation of an orbital, n = 4 and  = 0 is
4s.
Q.34 Chromium atom has six unpaired electrons.
Q.35 The energies of various subshells in the same Statement II : The electronic configuration of
shell are in the order of s > p > d > f. the ground state of an atom is the one which has
the greatest multiplicity.
Each of the questions given below consists of Q.42 Statement I : For n = 3,  = 0, 1 and 2 and m
Statement – I and Statement – II. Use the may be 0; 0, ± 1 and 0, ± 1 and ± 2.
following Key to choose the appropriate Statement II : For each value of n, there are 0
answer. to (n – 1) possible values of  and for each
(A) If both Statement - I and Statement - II are value of , there are 0 to ±  values of m.
true but Statement - II is not the correct Q.43 Statement I : The graph between 4r2dr 2
explanation of Statement – I. with r of 2s, 3p, 4d & 5f orbitals are identical in
shape.
(B) If both Statement- I and Statement- II are
Statement II : The number of planar nodes
true, and Statement - II is the correct
present in these orbitals is different.
explanation of Statement– I.
Q.44 Statement I : 2px, 2py and 2pz each have one
(C) If Statement - I is true but Statement - II is
nodal plane.
false.
Statement II : These orbital are degenerate
orbitals.
ATOMIC STRUCTURE 50
Column Matching : (B) n = 7  n = 3 (Q) Spectral lines in

Q.45 Column-I Column-II visible region

(A) 2s (P) Angular node = 1 (C) n = 5  n = 2 (R) 6 lines in the

(B) 1s (Q) Radial node = 0 spectrum

(C) 2p (R) Radial node = 1 (D) n = 6  n = 2 (S) Spectral lines in

(D) 3p (S) Angular node = 0 infrared region

Q.46 Column-I Column-II

(A) n = 6  n = 3 (P) 10 lines in the
spectrum

ANSWER KEY
LEVEL # 1

LEVEL # 2

LEVEL # 3

26. True 27. False 28. False 29. False 30. False 31. False 32. False 33. True 34. True
35. False 36. B 37. C 38. B 39. B 40. C 41. B 42. B 43. A
44. A 45. A  S,R; B  Q,S; C  Q,P; D  P,R 46. A  R,S; B  P,S; C  R,Q; D  P,Q

ATOMIC STRUCTURE 51