Dpp atomic structure_jh_sir-3573

PAGE NO. # 1
ETOOS ACADEMY Pvt. Ltd
F-106, Road No.2 Indraprastha Industrial Area, End of Evergreen Motor,
BSNL Lane, Jhalawar Road, Kota, Rajasthan (324005) Tel. : +91-744-242-5022, 92-14-233303
CHEMISTRY
DAILY PRACTICE PROBLEMS
D P P
COURSE NAME : UDAY (UB) DATE : 08.07.2013 to 13.07.2013 DPP NO. 11 TO 12
TARGET
JEE (ADVANCED) : 2015
* Marked Questions are having more than one correct option.
DPP NO. # 11
1. The mass of 1 mol of electrons is :
(A) 0.55 mg (B) 1.0008 g (C) 1.000 g (D) 0.184 g
2. Two nuclides A and B are isoneutronic. Their mass numbers are 76 and 77, respectively. If the atomic
number of A is 32, then the atomic number of B will be :
(A) 33 (B) 34 (C) 32 (D) 30
3. The isoelectronic pair of 32 electrons is :
(A) BO3
3– and CO3
2– (B) N2 and CO (C) PO4
3– and CO3
2– (D) All of the above
4. A diapositive ion has 16 protons. What is the number of electrons in its tetrapositive ion?
(A) 16 (B) 14 (C) 12 (D) 10
5. Calculate the frequency and wave number of a radiation having wavelength 600 nm.
6. Yellow light emitted from a sodium lamp has wavelength () of 580 nm. Find the frequency (v) and
wavenumber (v) of the yellow light.
7. Of the following, the radiation having the maximum wavelength is :
(A) UV rays (B) Radiowaves (C) X-rays (D) IR rays
8. Atomic radius of the order of 10–8 cm and nuclear radius is of the order of 10–13 cm. What fraction
of an atom is occupied by nucleus?
DPP NO. # 12
1. Calculate the number of photons emitted in 10 hours by a 60 W sodium lamp
( of photon = 2893 Å).
2. An electromagnetic radiation of wavelengths 242 nm is just sufficient to ionise a sodium atom.
Calculate the ionisation energy of sodium in kJ mol–1.
3. A bulb emits light of wavelength 4500 Å. The bulb is rated as 150 W and 8% of the energy is emitted
as light. How many photons are emitted by the bulb per second?

PAGE NO. # 2
4. In a photoelectric effect experiment, irradiation of a metal with light of frequency 5.2 × 1014 s–1 yields
electrons with maximum kinetic energy 1.3 × 10–19 J. Calculate the threshold frequency (0) for the
metal.
5. Light of wavelength 5000 Å falls on a metal surface of work function 1.9 eV. Find
a. The energy of photons.
b. The kinetic energy of photoelectrons.
6. A photon of 300 nm is absorbed by a gas, which then re-emits two photons. one re-emitted photon
has a wavelength of 400 nm. Calculate the energy of the other photon re-emitted out.
7. What is the number of photons of light with wavelength 300 nm that provide 2 J of energy?
8. A 100 W bulb is emitting light of wavelength 300 nm. Calculate the number of photons emitted by
the bulb in 1 min?
ANSWER KEY
DPP NO. # 11
1. (A) 2. (A) 3. (A) 4. (C) 5.
6 1
7
1 1
v 1.67 10 m
6 10 m


   
 
6. v =
6 1
7
1 1
1.72 10 m
5.80 10 m


  
 
7. (B) 8. VNucleus = 10–15 × VAtom
DPP NO. # 12
1. 6.41 × 1024 2. 8.21 × 10–19 J 3. 2.715 × 1019 4. 0 = 3.24 × 1014 s–1
5. a. E = 3.97 × 10–19 J b. KE = 3.97 × 10–19 J
6. ETotal = 1.656 × 10–19 J 7. 3.01 × 1018 photons.
8. 100 W bulb is emitting 100 J energy per second. So energy emitted in 1 min is 100 × 60 = 6000 J.

PAGE NO. # 1
CHEMISTRY
D P P
COURSE NAME : UDAY (UB) DATE : 15.07.2013 to 20.07.2013 DPP NO. 13 & 14
TARGET
DPP NO. # 13
1. When a certain metal was irradiated with light of frequency 4.0 × 1016 s–1, the photoelectrons emitted
had three times the kinetic energy as the kinetic energy of photoelectrons emitted when the metal was
irradiated with light of frequency 2.0 × 1016 s–1. Calculate the critical frequency (0) of the metal.
2. With what velocity should an -particle travel towards the nucleus of a copper atom to arrive at a
distance of 10–13 m from the nucleus of the copper atom?
3. Calculate the velocity of electron ejected from a platinum surface when radiation of 200 nm falls on
it. The work function of platinum is 5 eV. (1 eV = 1.6 × 10–19 J)
4. The dissociation energy of H2 is 430.53 kJ mol–1. If H2 is dissociated by illumination with radiation
of wavelength 253.7 nm, the fraction of the radiant energy which will be converted into kinetic energy
is given by :
(A) 8.86% (B) 2.33% (C) 1.3% (D) 90%
5. An iodine molecule dissociates into atoms after absorbing light of wave length 4500Å. If one quantum
of radiation is absorbed by each molecule, calculate the kinetic energy of iodine atoms. (Bond energy
of I2 is 240 kJ (mol)).
6. A dye absorbs light of  = 4530 Å. Assuming that under given conditions 47% of the absorbed energy
is re-emitted out as fluorescence, calculate the ratio of quanta emitted out to the number of quanta
absorbed.
7. With what velocity should an alpha (a) particle travel towards the nucleus of a copper atom to arrive
at a distance of 10–13 m from the nucleus of the copper atom?
8. A proton of mass 1.66 × 10–27 kg is moving with kinetic energy 5 × 10–27 J. What is the wavelength
of proton?
9. The energy required to ionise a helium atom is equal to 24.6 eV. The energy required to remove both
the electrons from the helium atom would be :
(A) 59 eV (B) 81 eV (C) 79 eV (D) 40 eV
DPP NO. # 14
1. Calculate the wavelength of the first line in the Balmer series of hydrogen spectrum.
2. Calculate the shortest wavelength in H spectrum of Lyman series when RH = 109,677 cm–1.
3. What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition
n = 4 to n = 2 of He spectrum?

PAGE NO. # 2
4. The ionisation energy of H atom is 13.6 eV. The ionisation energy of Li2+ ion will be :
(A) 54.4 eV (B) 122.4 eV (C) 13.6 eV (D) 27.2 eV
5. The wavelength of the first line in the Balmer series is 656 nm. Calculate the wavelength of the
second line and the limiting line in the Balmer series.
6. Calculate the wavelength of the first line and the series limit for the Lyman series for hydrogen.
7. A photon of 3000 Å is absorbed by a gas and then re-emitted as two photons. One photon is red
(7600Å). What would be the wavelength of the other photon?
8. Calculate the wavelength emitted during the transition of an electron in between two levels of Li2+ ion
whose sum is 4 and difference is 2.
9. The wavelength of series limit for Lyman series for He ion would be :
(A) 911.7 Å (B) 227.9 Å (C) 1215.1 Å (D) 303.8 Å
ANSWER KEY
DPP NO. # 13
1. v0 = 1 × 1016 s–1 2. v = 6.34 × 106 ms–1 3.
19
5 1
13
2(1.94 10 )
6.25 10 ms
(9.1 10 )




 

4. (A) 5. 0.216 × 10–19 J 6. 0.527 7. 6.325 × 106 m s–1.
8. 1.62 × 10–7 m 9. (C)
DPP NO. # 14
1. 656.5 nm 2. 911.7 Å 3. n1 = 1 and n2 = 2 4. (B)
5. 3647 Å. 6.  = 9.1176 × 10–6 cm
7. 4956.5 Å 8.  = 1.14 × 10–6 cm 9. (B)

PAGE NO. # 1
CHEMISTRY
D P P
TARGET
DPP No. # 15
1. Let v1
be the frequency of the series limit of the Lyman series, v2
be the frequency of the first line of the
Lyman series, and v3
be the frequency of the series limit of the Balmer series.
(A) v1
– v2
= v3
(B) v2
– v1
= v3
(C) 2 1 3
1
v (v v )
2
  (D) v1
+ v2
= v3
2. A certain transition in H spectrum from an excited state to the ground state in one or more steps gives rise
to a total of 10 lines. How many of these belong to the UV spectrum ?
(A) 3 (B) 4 (C) 6 (D) 5
3.* An electron jumps from the nth level to the first level. The correct fact(s) about H atom is/are
(A) Number of spectral lines =
n(n – 1)
2
(B) If n = 4, number of spectral lines = 6
(C) Number of spectral lines =
n(n 1)
2

(D) If n = 4, number of spectral lines = 10
4. The electron of H-atom in the ground state is excited to a higher energy level by monochromatic light of
energy 13.22 eV. How many different photons are emitted when it returns to the ground state ?
(A) 4 (B) 10 (C) 6 (D) 15
5. Ratio of frequency of revolution of electron in the second excited state of He
and second state of hydrogen
is :
(A)
32
27
(B)
27
32
(C)
1
54
(D)
27
2
6. The wave length of the first line of Lyman series of hydrogen is identical to that of second line of Balmer
series for some hydrogen like ion ‘X’. The IE2
for X is
(A) – 54.4 eV (B) – 328 eV (C) – 13.6 eV (D) – 3.8 eV
7. The ionisation energy of H atom is 13.6 eV. What will be the ionisation energy of He
and Li2+
ions ?
8. The angular momentum of an electron in a Bohr orbit of H atom is 4.2178 × 10–34
kg m2
s–1
. Calculate the
wavelength of the spectral line emitted when the electron falls from this level to the next lower level.
9. Find the energy released (in joules) when a doubly ionised helium ion (He2+
) takes up two electrons to form
a helium atom in the ground state. The first ionisation energy of a helium atom is 3.4 × 10–19
J.
10. Find the wave number corresponding to the longest wavelength photon required to removed an electron
from the second excited state of He
ion. (R = 1.097 × 107
m–1
).

PAGE NO. # 2
DPP No. # 16
1. One mole of He
ions is excited. An analysis showed that 50% of ions are in the third energy level, 25%
are in the second energy level, and the remaining are in the first energy level. Calculate the energy emitted
in kilojoules when all the ions return to the ground state.
2. Find out the number of waves made by a Bohr electron in one complete revolution in its third orbit.
3. An electron in a Bohr orbit of hydrogen atom in quantum level n2
has an angular momentum of
4.2176 × 10–34
kg m2 s–1
. If this electron drops from this level to the next lower, find the wavelength of this
spectral line. (Given RH
= 109679 cm–1
)
4. The circumference of the first Bohr orbit in H atom is 3.322 × 10–10
m. What is the velocity of the electron of this
orbit ?
5. The kinetic energy of an electron in H like atom is 6.04 eV. Find the area of the third Bohr orbit to which this
electron belongs. Also report the atom.
6. The energy of an electron in the first Bohr orbit of H atom is 13.6 eV. The possible energy value (s) of
excited state(s) for the electron in the Bohr orbit of hydrogen is/are :
(A) – 3.4 eV (B) – 4.2 eV (C) 6.8 eV (D) + 6.8 eV
7. If an electron in H atom has an energy of – 78.4 kcal mol–1
. The orbit in which the electron is present is :
(A) 1st (B) 2nd (C) 3rd (D) 4th
8. The difference between nth and (n + 1)th Bohr radius of H atom is equal to its (n – 1)th Bohr radius. The
value of n is :
(A) 1 (B) 2 (C) 3 (D) 4
9. Determine the frequency of revolution of an electron in the second Bohr orbit in hydrogen atom.
10. If the radius of the Bohr orbit is r then the de Brogile wavelength of the electron in the third orbit will be
(A) 2r (B)
2 r
3

(C)
3 r
3

(D) 6r
ANSWER KEY
DPP No. # 15
1. (A) 2. (B) 3.* (AB) 4. (D) 5. (A) 6. (C)
7. 122.4 eV 8. 1.8 × 10–4
cm 9. 9.02 × 10–18
J 10. 2.133 × 106
m–1
DPP No. # 16
1.
18 18 23 3 11 1
50% 2.176 10 4 1 25% 2.176 10 4 1 6 10 10 (kJ mol )
9 4
   
        
                
        
2. n = 3 3. 18756 Å 4. 2.19 × 106
m s–1
5. 17.8 × 10–16
cm2
6. (A) 7. (B)
8. (D) 9. 8.18 × 1014
Hz
10. (B)

PAGE NO. # 1
CHEMISTRY
D P P
TARGET
DPP No. # 17
1. If the speed of electron in the the first Bohr orbit of hydrogen atom is x, then the speed of the electron in the
third Bohr orbit of hydrogen is :
(A)
2
x
9
(B)
x
3
(C) 3x (D) 9x
2. The ratio of the difference between the first and second Bohr orbit energies to that between second and
third Bohr orbit energies is :
(A)
1
2
(B)
1
3
(C)
27
5
(D)
5
27
3.* Which of the following parameters are not same for all hydrogen-like atoms and ions in their ground state?
(A) Radius of orbit (B) Speed of electron
(C) Energy of the atom (D) Orbital angular momentum of electron
4. If the radius of first, second, third and fourth orbits of hydrogen atom are r1
, r2
, r3
and r4
respectively, then
their correct increasing order will be :
(A) r4
< r3
< r2
< r1
(B) r1
< r2
< r3
< r4
(C) r1
< r2
> r3
> r4
(D) Equal in all
5. The ratio of the radii of the fifth orbits of He
and Li
will be :
(A) 2 : 3 (B) 3 : 2 (C) 4 : 1 (D) 5 : 3
6. Which of the following orbits of hydrogen atom should have the values of their and radii in the ratio of 1 : 4?
(A) K and L (B) L and N (C) M and N (D) (A) and (B) are correct
7. The velocity of electron in a certain Bohr orbit of H atom bears the ratio 1 : 275 to the velocity of light.
a. What is the quantum number (n) of orbit?
b. Calculate the wave number of the radiation emitted when the electron jumps from (n + 1) state to the
ground state. (R = 1.0987 × 105
cm–1
)

PAGE NO. # 2
DPP No. # 18
1. An electron beam is accelerated by a potential difference of 1000 V. What is the wavelength of the wave
associated with the electron beam? (Mass of electron = 9.11 × 10–31
kg)
2. What is the ratio of the velocities of CH4
and O2
molecules so that they are associated with de Broglie
waves of equal wavelength?
3. A moving electron has 5 × 10–25
J of kinetic energy. What is the de Broglie wavelength?
4. A golf ball has a mass of 40 g and a speed of 45 ms–1
. If the speed can be measured with an accuracy of
2%, calculate the uncertainty in the position.
5. If the electron is to be located within 5 × 10–5
Å, what will be the uncertainty in its velocity?
6. If the uncertainties in the measurement of position and momentum of an electron are equal, calculate the
uncertainty in measuring the velocity.
7. If the uncertainty in the position of a moving electron is equal to its de Broglie wavelength, then its velocity
will be completely uncertain. Explain.
8. An electron with velocity v is found to have a certain value of de Broglie wavelength. The velocity that the
neutron should possess to have the same de Broglie wavelength is :
(A) v (B) v/1840 (C) 1840v (D) 1840/v
ANSWER KEY
DPP No. # 17
1. (B) 2. (C) 3.* (ABC) 4. (B) 5. (B) 6. (D)
7. v = 9.76 × 104
cm–1
DPP No. # 18
1. 0.123 × 10–10
m = 0.123 Å 2. VCH4
= 2 vO2
3. 6.95 × 10–7
m 4. 1.46 × 10–33
m
5. 16 × 1010
ms–1
6. v = 7.98 × 1012
m s–1
7.
p 1
p 4



(constant) 8. (B)

Dpp atomic structure_jh_sir-3573

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