CHEMISTRY

Q1. What transitioninthehydrogenspectrumhavethe same wavelengthasBalmer transition, n=4 to n=2of
He+
spectrum?
Q2. In case ofhydrogen atomwhen electronfalls fromhigher levelto M shell, the corresponding spectral
line willformthe part of:
(A) Balmer series (B) Lymanseries (C) Paschen series (D) Pfund series
Q3. Whichofthe following statement is incorrect ?
(A) The third quantumshellcanhold a maximumof18 electrons
(B)Anelectronfalling to the sameenergylevelfromanyhigherlevelalways emits thesame quantumof
energy
(C) The Balmer series oflines isinthe visible regionofthe emission spectrumofhydrogen atom
(D) Theelectron ofhydrogenatomin its ground stateremains in the first quantumshell
Q4. Totalnumber ofspectrallines when electronjumps from8thorbit to 2nd orbit:
(A) 6 (B) 36 (C) 21 (D) 38
Q5. Supposingtheelectronispresent inthe4thenergylevelofH-atom. Whenthe electronreturnsto ground
state the possible transitions would be :
(A) 4 1 (B) 42, 21 (C) 43, 32, 21 (D)All the above
Q6. The radiation is emitted when a hydrogenatomgoes froma highenergystate to a lower energystate.
The wavelength ofone line in visible region of atomic spectrumof hydrogen is 7
10
5
.
6 
 m. Energy
difference between the two states is:
(A) J
19
10
0
.
3 
 (B) J
18
10
0
.
1 
 (C) J
10
10
0
.
5 
 (D) .
10
5
.
6 7
J


Q7. Ritzcombinationprincipleis :
(A)










2
2
1
2
2 1
1
)
(
n
n
z
R
v H (B) 2
4
2
2
2
h
e
mz
En



(C)

hc
E  (D) none
Q8. The wavelengthofa spectralline for anelectronic transitionis inverselyrelated to :
(A) thenumber oforbitalundergoingthe transition.
(B) the nuclear charge ofan atom
(C) the differenceinenergylevels involvedinthe transition.
(D) thevelocityofthe electronundergoing the transition.
Q9. The hydrogenspectrumfroman incadescent source ofhydrogenis :
(A)Abandspectrumin emission (B)Alinespectruminemission
(C)Aband spectrumin absorption (D)Aline spectrumin absorption
Q10. Whichstatement relatingto the spectrumofH atomis false:
(A) The lines can be defined byquantumnumber
(B) Thelines oflongest wavelengthinthe Balmer seriescorresponds to the transitionbetweenn-3 and
n=2 levels
(C) The spectrallines are closer togetherat longer wavelength
(D)Acontinuumoccurs at 

n

Q11. Fillinthe blanks :
(i) The light radiations with discrete quantities ofenergyare called ...... . (I.I.T. 1993)
(ii) 
/
h isthe angular momentumofthe electron in the ..........orbit ofHe+
. (R.E.E. 1990)
(iii) The transition ofthe electron inhydrogenatomfromfourth to thefirst energystate emitsa spectralline
which fallsin........... series. (R.E.E. 1990)
Q12. The observation ofline spectrumofhydrogenatomindicates that
(A) the electronsdo not lose energywheninstationarystates
(B) there is emission ofenergywhen a sample ofhydrogen is heated
(C) anelectron inexcited state loss energycontinuously
(D) an electronin excited state loses energyin the formof bundles or packets ofenergy
Q13. Lines ofLymanseries ofspectrumofhydrogenare in
(A)ultraviolet region (B) infrared region
(C) visible region (D) farinfrared region (E) none ofthe above
Q14. Whentheelectronofhydrogenatomreturnto Lshellfromshellsofhigherenergy, we get aseries oflines
in the spectrum. This series is called
(A) Balmer series (B) Lymanseries (C) Brackett series (D) Paschen series
Q15. Inhydrogenatoms electrons are excitedto the 5th quantumlevel. How manydifferent lines mayappear
inthespectrum
(A) 4 (B) 12 (C) 8 (D) 10
Q16. A certaintransition in the hydrogenspectrumfroman excitedstate in one or more steps gives riseto a
totaloften lines. Number oflines lying invisible spectrumis
(A) 3 (B) 4 (C) 5 (D) 6
Q17. The wave number of the first Lyman transition in H atom spectrum is equal to the wave number of
second balmer transitioninthe spectrumof
(A) Li2+
(B) Be3+
(C) He+
(D) B4+
Q18. InBohrseries oflines ofhydrogenspectrum, the thirdline fromthe redend corresponds to whichone of
the followinginter-orbit inanatomofhydrogen
(A) 1
4  (B) 5
2  (C) 2
3  (D) 2
5 
Q19. The wavelengthoftheradiationemitted,wheninahydrogenatomelectronfalls frominfinityto stationary
state 1, would be (Rydberg constant = 1
_
7
10
097
.
1 m
 )
(A) 406nm (B)192 nm (C) 91 nm (D) nm
8
10
1
.
9 

Q20. Acertainatomic transitionfromanexcited stateto thegroundstate ofthehydrogenatominoneormore
steps give rise to four line inthe ultraviolet region ofthe spectrum. How manylines does this transition
produce inthe infrared region ofthe spectrum
(A) 1 (B) 2 (C) 3 (D) 6
Q21. The masses ofphotons corresponding to the first lines ofLymanand Balmer series ofthe spectrumof
hydrogen atomare in the ratio of
(A) 27 : 5 (B) 3 : 2 (C) 2 : 3 (D) 4 : 9
Q22. Iftheseries limit ofwavelengthofthe Lymanseries for the hydrogenatomis 912Å, thenthe serieslimit
ofwavelength for the Balmer series ofradiationwhichmaybe emitted is :
(A) 912 Å (B) 912 2 Å (C) 912 4Å (D) 912/2 Å

Q23. What transitioninHe+
ionshallhave thesame wave numberas the first lineinBalmer seriesofhydrogen
atom:
(A) 2
3  (B) 4
6  (C) 3
5  (D) 5
7 
Q24. An atomemits energyequalto 12
10
4 
 erg .To which part of electromagnetic spectrumit belongs :
(A) UV region (B)Visible region (C) IR region (D) Microwave region
Q25. Ametalsurface emits photo electrons, whenthe incident radiationpossesses minimum.....
(A) Frequency (B)Intensity (C)Velocity (D) Wave-length
Q26. Electromagnetic radiatiationsoffrequency ‘v’consists ofa streamofparticles called photons. Whichof
the following statements is / are trueabout photons :
(A) as the frequencyincreases, the number ofphotons inthe beamincreases.
(B) as the intensityoflight increases ‘ the number ofphotons in the beamincreases.
(C) the number ofphotons inthe beamare independent offrequency
(D) the number ofphotons in the beamare independent oftheintensityoflight.
Q27. Inphotoelectriceffect, the saturationphotocurrent:
(A) Increases withincrease offrequencyofincident photon
(B) Decreaseswith increase offrequencyofincident photon
(C) Does not depend on thefrequencyofphoton but depends onlyon intensityofincident light
(D) Depends bothon intensityand frequencyofthe incident Photon
Q28. A photon-sensitivemetalis not emitting photoelectronwhen irradiated. It willdo so whenthresholdis
crossed. To cross the threshold we need to increase:
(A) Intensity (B) Frequency (C) Wavelength (D) none
Q29. The photoelectric effect is described as the ejection ofelectrons fromthe surface ofametalwhen:
(A) It is heated to ahigh temperature (B) Electronsofsuitable velocityimpingeonit
(C) Light ofsuitable wavelength fallsonit (D) It is placed ina strong magnetic field
Q30. Photoelectric effect shows :
(A) Particle-likebehavior oflight (B)Wave-like behavior oflight
(C) Bothwave-like and particle-like behavior oflight
(D) Neither wave-like nor particle-like behavioroflight
Q31. The photoelectriceffect occurs onlywhenthe incident light hasmore frequencythana certainminium:
(A) Frequency (B)Wavelength (C) Speed (D) Charge
Q32. Whenthe frequencyoflight incident ona metallic plate isdouble, the KE ofthe emittedphotoelectrons
willbe :
(A) Doubled
(B) Halved
(C) Increased but more than doubled ofthe previous KE
(D) Unchanged
Q33. Asurface ejectselectrons whenhitted bygreenlight but not.Whenhitted byyellow light. Willelectrons
be ejected ifthe surface is hitted byred light:
(A)Yes
(B) No
(C)Yes, ifthe red beamis quite intense
(D)Yes, ifthe red beamcontinues to falluponthe surface for a long time

Q34. The work functionfor a metalis 4 eV. To emit a photo electron ofzero velocityfromthe surface ofthe
metal, thewavelengthofincident light should be :
(A) 2700Å (B) 1700 Å (C) 5900 Å (D) 3100 Å
Q35. Photoelectric effect isthe phenomenonin which
(A) Photons come out of a metalwhen it is hit bya beamofelectrons.
(B) Photons come out ofthenuclues ofan atomunder the action ofan electric field
(C) Electronscome out ofa metalwith a constant velocitywhichdepends onthe frequencyand
intensityofincident light wave.
(D) Electrons come out ofametalwithdifferent velocitiesnot greater thana certainvalue which
depends onlyonthe frequencyofthe incident light wave and not on its intensity.
Q36. Inphotoelectriceffect, the photocurrent
(A) Increaseswithincreasing frequencyofincident photon.
(B) Decreaseswithincreasing frequencyofincident photon
(C) Does not depend on the frequencyofphoton
(D) Depends bothon intensityand frequencyofthe incident photon
Q37. Photoelectric effect canbe caused by
(A) visible light but not X-rays (B) Gamma rays but not byX-rays
(C) U.V. light only (D) Visible light, U.V. rays and Gamma rays also
Q38. Photoelectric effect shows
(A) Particlenature oflight (B) wavenature oflight
(C) dualnature oflight (D) neither ofthe natures oflight
Q39. Whenlight is directed at the metalsurface, the emitted electrons
(A) are called photons
(B) haverandomenergies
(C) have energies that depend uponthe frequencyoflight
(D) have energiesthat depend upon theintensityoflight
(E) have energiesless than the energyofincident photons
Q40. If λ L
, λ m
and λ N
are the wave lengths of electron in L, M, N energy levels of H-atom respectively.
.
What is their decreasing order:
(A) λ L
> λ M
>λ N
(B) λ L
< λ M
<λ N
(C) λ L
> λ M
<λ N
(D) λ L
< λ M
>λ N
Q41. The wave- lengthofa moving electron-
(A) Increases withthe increase ofthe velocityofthe electron
(B) Does not depend upon the velocityofthe electron
(C) Decreases withthe increase ofvelocityofthe electron
(D) Is equalto zero
Q42. How fast is an electron moving ifit has awavelength equalto thedistance it travels inone second?
(A)
m
h
(B)
h
m
(C)
p
h
(D)
)
(
2 KE
h
Q43. Iftravellingat equalspeeds, thelongest wavelengthofthefollowing matter waves is that for a:
(A) electron (B) proton (C) neutron (D) alpha particle )
( 2
He .
Q44. The Heisenberg’s uncertaintyprinciple canbeapplied to :
(A)Acricket ball (B)Afootball (C)Ajet aeroplane (D)Anelectron

Q45. The de Broglie wavelength ofa tennis ball of 60 g moving with a velocity of 10 meters per second is
approximately
(A) 10–16
meters (B) 10–25
meters (C) 10–33
meters (D) 10–31
meters
Q46. It is not true that
(A) The wavelengthassociated withan electronis longer that ofproton iftheyhavethe same speed
(B) violet radiations have a longer wavelengththat red radiations
(C) the energyoflight withwavelength 600 nmis lower thanwith wavelength500 nm
(D) spectrumofan atomis knownas line spectrum
Q47. The condition for a stable wave is
(A) r
n 
 6
 (B) r
n 

2
1
 (C) r
n 
 8
 (D) r
n 
 4

Q48. Number ofwaves formed byaBohr electron in one complete revolution in its third orbit is
(A) 0 (B) 1 (C) 2 (D) 3
Q49. Bohr modelofatomis contradicted by
(A) Pauli’sexclusionprinciple (B) Plankquantumtheory
(C) Heisenberguncertaintyprinciple (D) allthe above
Q50. Heisenberg uncertaintyprincipleis not valid for:
(A) Movingelectrons (B) Motor car (C) Stationaryparticles (D)All
Q51. What accelerating potentialmust be imparted to a proton beamto give it aneffective = 0.05 Å.
(V=33 volt) (mp
= 1.672 x 10–27
kg)
Q52. Calculate the associated withan electron moving withthevelocityoflight.
Q53. The K.E. ofan electron is 4.55 x 10–25
J Calculate its .
Q54. Calculate the  ofCO2
molecule moving with a velocity440 m/s.
Q55. Show that the De-Broglie  ofthe electron in nthBohr orbit is proportionalto n (no. oforbit)
Q56. The De-broglie ofelectroninthe 2st Bohr orbit is
(A) r1
(B) 4r1
(C) 2r1
(D) 6r1
For Assertion–Reason type questions
(A) If both assertion and reason are true and reason is the correct explanation of assertion
(B) If both assertion and reason are true but reason is not the correct explanation of
assertion
(C) If assertion is true but reason is false
(D) If both assertion and reason are false
(E) If assertion is false but reason is true
Q57. Assertion : Hydrogen hasonlyelectron in its orbit but it produces severallines.
Reason : There are manyexcited energylevels available.
Q58. Assertion: Line emission spectrahels in the studyofelectronic spectra.
Reason: Eachelement has a unique line emissionspectrum.
Q59. Assertion: On increasing the intensityofincident radiation, the number ofphotoelectrons ejected
and their K.E. increase.
Reason: Greater the intensitymeans greater thetotalenergy

Q60. Assertion: Electronareejected fromacertainmetalwheneither blueor violet light strikesthe metal
surface. However, onlyviolet light causes electron ejectionfroma second metal.
Reason : The electroninthe first metalrequire lessenergyfor ejection.
Q61. Assertion: The kinetic energyofthe photoelectronejected increases withincrease inintensityof
incident light.
Reason: Increase in intensityofincident light increase therate ofemission
Q62. Assertion: Threshold frequencyis a characterstic for a metal.
Reason: Thresholdfrequencyisa maximumfreuencyrequiredfor the ejectionofelectronfomthe
metalsurface.
Q63. Assertion: Matter wavesconsist ofoscillating electricand magnetic fields.
Reason: Matter waves requiremediumfor propagation.
ANSWERS:
Q1. 2  1 Q2. C Q3. B Q4. C Q5. D
Q6. A Q7. A Q8. B Q9. B Q10. C
Q11. (i) quanta (ii)IInd (iii) Lyman Q12. D Q13. A Q14. A
Q15. D Q16. A Q17. C Q18. D Q19. C
Q20. C Q21. A Q22. C Q23. B Q24. B
Q25. A Q26. BC Q27. C Q28. B Q29. C
Q30. A Q31. A Q32. C Q33. B Q34. D
Q35. D Q36. C Q37. D Q38. A Q39. CE
Q40. B Q41. C Q42. A Q43. A Q44. D
Q45. C Q46. B Q47. C Q48. D Q49. C
Q50. BC Q52. 2.5 x 10–12
m Q53. 97.2 x 10–7
m Q54.  = 2.06 x 10–11
Q56. B
Q57. A Q58. A Q59. D Q60. A Q61. E
Q62. C Q63. E