Modern Physics KPP PYQ Question Notes Lakshya JEE 2025 PDF

1 Lakshya JEE (2025) Modern Physics 1. An electron (of mass m) and a photon have the same 5. In the given figure, the energy levels of hydrogen energy E in the range of a few eV. The ratio of the...

1 Lakshya JEE (2025) Modern Physics 1. An electron (of mass m) and a photon have the same 5. In the given figure, the energy levels of hydrogen energy E in the range of a few eV. The ratio of the atom have been shown along with some transitions de-Broglie wavelength associated with the electron marked A, B, C, D and E. The transitions A, B and C and the wavelength of the photon is (c = speed of light respectively represent: (JEE Main 2020) in vacuum) (JEE Main 2020) 1/2  E  (1)    2m  1/2 1 E  c  2m  (2) (3) c(2mE)1/2 1/2 1  2E  c  m  (4) (1) The ionization potential of hydrogen, second member of Balmer series and third member of 2. A beam of electromagnetic radiation of intensity Paschen series. 6.4 × 10–5 W/cm2 is comprised of wavelength, (2) The first member of the Lyman series, third λ = 310 nm. It falls normally on a metal (work member of Balmer series and second member of function φ = 2eV) of surface area of 1 cm2. If one in Paschen series. 103 photons ejects an electron, total number of (3) The series limit of Lyman series, third member electrons ejected in 1 s is 10x. (hc = 1240eVnm, 1eV = 1.6 × 10–19 J), then x of Balmer series and second member of Paschen is_________. (JEE Main 2020) series. (4) The series limit of Lyman series, second 3. The time period of revolution of electron in its ground member of Balmer series and second member of state orbit in a hydrogen atom is 1.6 × 10–16 s. The Paschen series. frequency of revolution of the electron in its first excited state (in s–1) is: (JEE Main 2020) 6. An electron (mass m) with initial velocity (1) 6.2 × 1015 (2) 5.6 × 1015 (3) 7.8 × 1014 (4) 1.6 × 1015 v = v0iˆ + v0 ˆj is in an electric field E = −E0kˆ. If λ0 is initial de-Broglie wavelength of 4. When photon of energy 4.0 eV strikes the surface of electron, its de-Broglie wave length at time t is given a metal A, the ejected photo electrons have maximum by: (JEE Main 2020) kinetic energy TA eV end de-Broglie wavelength λA. 0 2 0 The maximum kinetic energy of photoelectrons (1) (2) 2 2 2 eEt 1+ 2 2 e2 E 2 t 2 liberated from another metal B by photon of energy 2+ 2 4.50 eV is TB = (TA – 1.5)eV. If the de-Broglie m v0 m 2 + v02 wavelength of these photoelectrons λB = 2λA, then the 0 0 (3) (4) work function of metal B is: (JEE Main 2020) 2 eEt 2 2 1+ e2 E02 t 2 (1) 3 eV (2) 2 eV 1+ 2m2v02 m2 v02 (3) 4 eV (4) 1.5 eV  2 7. The first member of the Balmer series of hydrogen 13. In a hydrogen atom the electron makes a transition atom has a wavelength of 6561 Å. The wavelength of from (n + 1)th level to the nth level. If n >> l, the the second member of the Balmer series (in nm) is: frequency of radiation emitted is proportional to: (JEE Main 2020) (JEE Main 2020) 1 1 (1) (2) 8. A particle moving with kinetic energy E has de n4 n3 Broglie wavelength λ. If energy ∆E is added to its (3) 1 (4) 1 energy, the wavelength become λ/2. Value of ∆E, is: n2 n (JEE Main 2020) (1) 2E (2) E 14. A particle is moving 5 times as fast as an electron. (3) 3E (4) 4E The ratio of the de-Broglie wavelength of the particle to that of the electron is 1.878 × 10–4. The mass of the 9. Radiation, with wavelength 6561Å falls on a metal particle is close to: (JEE Main 2020) surface to produce photoelectrons. The electrons are (1) 4.8 × 10 kg–27 –28 (2) 1.2 × 10 kg made to enter a uniform magnetic field of (3) 9.1 × 10–31 kg (4) 9.7 × 10–28 kg 3 × 10–4 T. If the radius of the largest circular path followed by the electrons is 10 mm, the work function 15. When the wavelength of radiation falling on a metal of the metal is close to: (JEE Main 2020) is changed from 500 nm to 200 nm, the maximum (1) 1.8 eV (2) 1.1 eV kinetic energy of the photoelectrons becomes three (3) 0.8 eV (3) 1.6 eV times larger. The work function of the metal is close to: (JEE Main 2020) 10. The energy required to ionise a hydrogen like ion in its ground state is 9 Rydbergs. What is the (1) 0.61 eV (2) 0.52 eV wavelength of the radiation emitted when the electron (3) 0.81 eV (4) 1.02 eV in this ion jumps from the second excited state to the ground state? (JEE Main 2020) 16. The radius of R of a nucleus of mass number A can (1) 35.8 nm (2) 24.2 nm be estimated by the formula R = (1.3 × 10–15)A1/3 m. (3) 8.6 nm (4) 11.4 nm It follows that the mass density of a nucleus is of the order (Mprot ≅ Mneut ≃ 1.67 × 10–27 kg) (JEE Main 2020) 11. An electron of mass m and magnitude of charge |e| (1) 1024 kg m–3 (2) 103 kg m–3 initially at rest gets accelerated by a constant electric (3) 1017 kg m–3 (4) 1010 kg m–3 field E. The rate of change of de-Broglie wavelength of this electron at time t ignoring relativistic effects 17. Hydrogen ion and singly ionized helium atom are is: (JEE Main 2020) accelerated, from rest, through the same potential difference. The ratio of final speeds of hydrogen and −h | e | Et helium ions is close to: (JEE Main 2020) (1) 2 (2) | e | Et h (1) 5 : 7 (2) 1 : 2 (3) 10 : 7 (4) 2 : 1 h h (3) (4) − | e | Et 2 | e | Et 18. Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. 12. When radiation of wavelength λ is used to illuminate The ratio of the number density of photons of X-rays a metallic surface, the stopping potential is V. When to the number density of photons of the visible light the same surface is illuminated with radiation of of the given wavelengths is: (JEE Main 2020) V 1 wavelength 3λ, the stopping potential is. If the (1) (2) 500 4 500 threshold wavelength for the metallic surface is nλ 1 (3) 250 (4) then value of n will be _______. (JEE Main 2020) 250  3 19. Given figure shows few data points in a photo electric 23. The surface of a metal is illuminated alternately with effect experiment for a certain metal. The minimum photons of energies E1 = 4eV and E2 = 2.5 eV energy for ejection of electron from its surface is: respectively. The ratio of maximum speeds of the (Plancks constant h = 6.62 × 10–34 J.s) photoelectrons emitted in the two cases is 2. The (JEE Main 2020) work function of the metal in (eV) is ______. (JEE Main 2020) 24. An electron, a doubly ionized helium ion (He++) and a proton are having the same kinetic energy. The relation between their respective de-Broglie wavelengths  e , He++ and  p is: (JEE Main 2020) (1) 2.27 eV (2) 2.59 eV (1) e   p  He++ (3) 1.93 eV (4) 2.10 eV (2)  p  He++ =  p m (3) e  He++   p 20. Particle A of mass mA = moving along the x-axis 2 (4) e   p  He++ with velocity v0 collides elastically with another m particle B at rest having mass mB =. If both 25. You are given that Mass of 37 Li = 7.0160u. Mass of 3 2 He = 4.0026u = 1.0079u. When 4 1 particles move along the x-axis after the collision, the and mass of 1H change ∆λ in de-Broglie wavelength of particle A, in 20 g of 3 7 Li is converted into 2 4 He by proton terms of its de-Broglie wavelength (λ0) before capture, the energy liberated, (in kWh), is: collision is: (JEE Main 2020) [Mass of nudeon = 1 GeV/c2] (JEE Main 2020) 5 6 (1)  =   (2)  =  (1) 8 × 10 2 (2) 1.33 × 106 3 (3) 6.82 × 105 (3)  = 2  (4)  =  2 (4) 4.5 × 105 21. In the line spectra of hydrogen atom, difference 26. Assuming the nitrogen molecule is moving with between the largest and the shortest wavelengths of r.m.s. velocity at 400K, the de-Broglie wavelength of the Lyman series is 304Å. The corresponding nitrogen molecule is close to: (Given: nitrogen difference for the Paschan series nÅ is: ______. (JEE Main 2020) molecule weight : 4.64 × 10–26 kg, Boltzman constant : 1.38 × 10–23 J/K, Planck constant : 6.63 × 10–34 J.s) 22. In a photoelectric effect experiment, the graph of (JEE Main 2020) stopping potential V versus reciprocal of wavelength (1) 0.34 Å (2) 0.24 Å obtained is shown in the figure. As the intensity of (3) 0.20 Å (4) 0.44 Å incident radiation is increased: (JEE Main 2020) 27. Find the binding energy per nucleon for 120 50 Sn. Mass of proton mP = 1.00783 U, mass of neutron mn = 1.00867 U and mass of tin nucleus mSn = 119.902199 U. (take 1U = 931 MeV) (1) Slope of the straight line get more steep (JEE Main 2020) (2) Straight line shifts to left (1) 8.5 MeV (2) 7.5 MeV (3) Graph does not change (3) 8.0 MeV (4) 9.0 MeV (4) Straight line shifts to right  4 28. The graph which depicts the results of Rutherford 31. An X-ray tube is operated at 1.24 million volt. The gold foil experiment with α-particles is: θ: Scattering shortest wavelength of the produced photon will be: angle Y: Number of scattered α-particles detected (JEE Main 2021) (Plots are schematic and n to scale) (JEE Main 2020) (1) 10–3 nm (2) 10–1 nm (3) 10–2 nm (4) 10–4 nm (1) 32. According to Bohr atom model, in which of the following transitions will the frequency be maximum? (JEE Main 2021) (1) n = 4 to n = 3 (2) n = 2 to n = 1 (3) n = 5 to n = 4 (2) (4) n = 3 to n = 2 33. An α particle and a proton are accelerated from rest by a potential difference of 200 V. After this, their de Broglie wavelengths are λα and λP respectively. The ratio λp/λα is: (JEE Main 2021) (1) 3.8 (2) 8 (3) (3) 7.8 (4) 2.8 34. The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n = 2 to n = 1 state is: (JEE Main 2021) (1) 194.8 nm (2) 913.3 nm (3) 490.7 nm (4) 121.8 nm (4) 35. An electron of mass me and a proton of mass mP = 1836 me are moving with the same speed. The  ratio of their de Broglie wavelength electron will be: proton (JEE Main 2021) 29. Given below are two statements: (1) 1839 (2) 1 Statement-I: Two photons having equal linear (3) 918 (4) 1/1836 momenta have equal wavelengths. Statement-II: If the wavelength of photon is 36. The stopping potential for electrons emitted from a decreased, then the momentum and energy of a photosensitive surface illuminated by light of photon will also decrease. wavelength 491 nm is 0.710 V. When the incident In the light of the above statements, choose the wavelength is changed to a new value, the stopping correct answer from the options given below. potential is 1.43 V. The new wavelength is: (JEE Main 2021) (JEE Main 2021) (1) Both Statement I and Statement II are true (1) 329 nm (2) 309 nm (2) Statement I is false but Statement II is true (3) 382 nm (4) 400 nm (3) Both Statement I and Statement II are false (4) Statement I is true but Statement II is false 37. The wavelength of an X-ray beam is 10Å. The mass of a fictitious particle having the same energy as that 30. The de Broglie wavelength of a proton and α-particle x are equal. The ratio of their velocities is: of the X-ray photons is h kg. The value of x (JEE Main 2021) 3 (1) 4 : 3 (2) 4 : 1 is_________. (h = Planck's constant) (3) 4 : 2 (4) 1 : 4 (JEE Main 2021)  5 38. If λ1 and λ2 are the wavelengths of the third member 43. The first three spectral lines of H-atom in the Balmer of Lyman and first member of the Paschen series series are given λ1, λ2, λ3 considering the Bohr respectively, then the value of λ1 : λ2 is: atomic model, the wave lengths of first and third (JEE Main 2021)   spectral lines  1  are related by a factor of (1) 1 : 9 (2) 7 : 108  3  (3) 7 : 135 (4) 1 : 3 approximately 'x' × 10–1. The value of x, to the nearest integer, is ________. (JEE Main 2021) 39. Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. 44. The de-Broglie wavelength associated with an Assertion A: An electron microscope can achieve electron and a proton were calculated by accelerating them through same potential of 100 V. What should better resolving power than an optical microscope. nearly be the ratio of their wavelengths? Reason R: The de Broglie's wavelength of the (mP = 1.00727 u, me = 0.00055u) (JEE Main 2021) electrons emitted from an electron gun is much less (1) 1860 : 1 (2) (1860)2 : 1 than wavelength of visible light. (3) 41.4 : 1 (4) 43 : 1 In the light of the above statements, choose the correct answer from the options given below: 45. If an electron is moving in the nth orbit of the (JEE Main 2021) hydrogen atom, then its velocity (vn) for the nth orbit (1) A is true but R is false. is given as: (JEE Main 2021) 1 (2) Both A and R are true and R is the correct (1) vn  n (2) vn  explanation of A. n 1 (3) Both A and R are true but R is NOT the correct (3) vn  n2 (4) vn  2 explanation of A n (4) A is false but R is true. 46. An electron of mass m and a photon have same energy E. The ratio of wavelength of electron to that 40. The recoil speed of a hydrogen atom after it emits a of photon is: (c being the velocity of light) photon in going from n = 5 state to n = 1 state will be: (JEE Main 2021) (JEE Main 2021) 1/2 1/2 (1) 4.17 m/s (2) 2.19 m/s 1  2m  1 E  c  E  c  2m  (1) (2) (3) 3.25 m/s (4) 4.34 m/s 1/2  E  41. Two stream of photons, possessing energies equal to (3)   (4) c(2mE)1/2  2m  twice and ten times the work function of metal are incident on the metal surface successively. The value 47. If 2.5 × 10–6 N average force is exerted by a light of ratio of maximum velocities of the photoelectrons wave on a non-reflecting surface of 30 cm2 area emitted in the two respective cases is x : y. The value during 40 minutes of time span, the energy flux of of x is _______ (JEE Main 2021) light just before it falls on the surface is ____ W/cm2. (Round off to the Nearest Integer) 42. The stopping potential in the context of photoelectric (Assume complete absorption and normal incidence conditions are there) (JEE Main 2021) effect depends on the following property of incident electromagnetic radiation: (JEE Main 2021) 48. The atomic hydrogen emits a line spectrum (1) Phase consisting of various series. Which series of (2) Intensity hydrogen atomic spectra is lying in the visible (3) Amplitude region? (JEE Main 2021) (4) Frequency (1) Brackett series (2) Paschen series (3) Lyman series (4) Balmer series  6 49. Two identical photocathodes receive the light of 54. The radiation corresponding to 3 → 2 transition of a frequencies f1 and f2 respectively. If the velocities of hydrogen atom falls on a gold surface to generate the photo-electrons coming out are v1 and v2 photoelectrons. These electrons are passed through a respectively, then (JEE Main 2021) magnetic field of 5 × 10–4 T. Assume that the radius 2h (1) v12 − v22 = [ f1 − f 2 ] of the largest circular path followed by these m 2h electrons is 7 mm, the work function of the metal is: (2) v12 + v22 = [ f1 − f 2 ] (Mass of electron = 9.1 × 10–31 kg). (JEE Main 2021) m 1/2 (1) 1.36 eV (2) 1.88 eV  2h  (3) v1 + v2 =  ( f1 − f 2 ) (3) 0.16 eV (4) 0.82 eV m  1/2  2h  55. An electron having de-Broglie wavelength λ is (4) v1 − v2 =  ( f1 − f 2 )  m  incident on a target in a X-ray tube. Cut-off wavelength of emitted X-ray is: (JEE Main 2021) 50. A particle of mass m moves in a circular orbit in a 2m2c22 (1) 0 (2) central potential field U(r) = U0r4. If Bohr's h2 quantization conditions are applied, radii of possible 2mc2 hc orbitals rn vary with n1/α, where α is ________. (3) (4) (JEE Main 2021) h mc 51. Imagine that the electron in a hydrogen atom is 56. A certain metallic surface is illuminated by replaced by a muon (μ). The mass of muon particle is monochromatic radiation of wavelength λ. The 207 times that of an electron and charge is equal to stopping potential for photoelectric current for this the charge of an electron. The ionization potential of radiation is 3V0. If the same surface is illuminated this hydrogen atom will be :- (JEE Main 2021) with a radiation of wavelength 2λ, the stopping (1) 13.6 eV (2) 2815.2 eV potential is V0. The threshold wavelength of this (3) 331.2 eV (4) 27.2 eV surface for photoelectric effect is _____λ. (JEE Main 2021) 52. A particle is travelling 4 times as fast as an 57. An electron of mass me and a proton of mass mP are wavelength of a particle to that of electron is 2 : 1, the accelerated through the same potential difference. mass of the particle is electron. Assuming the ratio of The ratio of the de-Broglie wavelength associated de-Broglie. (JEE Main 2021) with the electron to that with the proton is :- 1 (1) times the mass of e– (JEE Main 2021) 16 mp (2) 8 times the mass of e– (1) (2) 1 me (3) 16 times the mass of e– 1 mp me (4) times the mass of e– (3) (4) 8 me mp 53. A proton and an α-particle, having kinetic energies 58. What should be the order of arrangement of KP and Kα, respectively, enter into a magnetic field at de-Broglie wavelength of electron (λe), an a-particle right angles. The ratio of the radii of trajectory of proton to that of α-particle is 2 : 1. The ratio of (λα) and proton (λP) given that all have the same KP : Kα is: (JEE Main 2021) kinetic energy? (JEE Main 2021) (1) 1 : 8 (2) 8 : 1 (1) λe = λp = λα (2) λe < λp < λα (3) 1 : 4 (4) 4 : 1 (3) λe > λp > λα (4) λe = λp > λα  7 59. A particle of mass 4M at rest disintegrates into two 65. The Kα X-ray of molybdenum has wavelength particles of mass M and 3M respectively having non.071 nm. If the energy of a molybdenum atoms with zero velocities. The ratio of de- Broglie wavelength a K electron knocked out is 27.5 keV, the energy of of particle of mass M to that of mass 3M will be: (JEE Main 2021) this atom when an L electron is knocked out will be (1) 1 : 3 (2) 3 : 1 ______ keV. (Round off to the nearest integer) (3) 1: 3 (4) 1 : 1 [h = 4.14 × 10–15 eVs, c = 3 × 108 ms–1] (JEE Main-2021) 60. When radiation of wavelength λ is incident on a metallic surface, the stopping potential of ejected 66. A particular hydrogen like ion emits radiation of photoelectrons is 4.8 V. If the same surface is frequency 2.92 × 1015 Hz when it makes transition illuminated by radiation of double the previous from n = 3 to n = 1. The frequency in Hz of radiation wavelength, then the stopping potential becomes emitted in transition from n = 2 to n = 1 will be: 1.6 V. The threshold wavelength of the metal is: (JEE Main-2021) (JEE Main-2021) 15 15 (1) 0.44 × 10 (2) 6.57 × 10 (1) 2 λ (2) 4 λ (3) 8 λ (4) 6 λ (3) 4.38 × 1015 (4) 2.46 × 1015 61. A light beam of wavelength 500 nm is incident on a 67. In a photoelectric experiment ultraviolet light of metal having work function of 1.25 eV, placed in a wavelength 280 nm is used with lithium cathode magnetic field of intensity B. The electrons emitted having work function ϕ = 2.5 eV. If the wavelength perpendicular to the magnetic field B, with maximum kinetic energy are bent into circular arc of radius of incident light is switched to 400 nm, find out the 30 cm. The value of B is _______ × 10–7 T. Given change in the stopping potential. hc = 20 × 10–26 J–m, mass of electron = 9×10–31 kg –34 8 –1 (h = 6.63 × 10 Js, c = 3 × 10 ms ) (JEE Main-2021) (JEE Main-2021) (1) 1.3 V (2) 1.1 V 62. From the given data, the amount of energy required (3) 1.9 V (4) 0.6 V 13 to break the nucleus of aluminium 27 Al –3 68. The de-Broglie wavelength of a particle having is _____ x × 10 J. kinetic energy E is λ. How much extra energy must Mass of neutron = 1.00866 u be given to this particle so that the de- Broglie Mass of proton = 1.00726 u wavelength reduces to 75% of the initial value? (JEE Main-2021) Mass of Aluminium nucleus = 27.18846 u 1 7 (Assume 1 u corresponds to x J of energy) (1) E (2) E 9 9 (Round off to the nearest integer) (JEE Main-2021) 16 (3) E (4) E 9 63. In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius 0.5Å. If the speed 69. In a photoelectric experiment, increasing the intensity of electron is 2.2 × 166 m/s, then the current of incident light: (JEE Main-2021) associated with the electron will be _____ × 10–2 mA. (1) increases the number of photons incident and 22 also increases the K.E. of the ejected electrons [Take π as ] (JEE Main-2021) 7 (2) increases the frequency of photons incident and increases the K.E. of the ejected electrons. 64. A particle of mass 9.1 × 10–31 kg travels in a medium (3) increases the frequency of photons incident and with a speed of 106 m/s and a photon of a radiation of the K.E. of the ejected electrons remains linear momentum 10–27 kg m/s travels in vacuum. The unchanged wavelength of photon is _______ times the (4) increases the number of photons incident and the wavelength of the particle. (JEE Main-2021) K.E. of the ejected electrons remains unchanged  8 70. A monochromatic neon lamp with wavelength of 75. The temperature of an ideal gas in 3-dimensions is 670.5 nm illuminates a photo-sensitive material 300 K. The corresponding de-Broglie wavelength of which has a stopping voltage of 0.48 V. What will be the electron approximately at 300 K, is: [me = mass of electron = 9 × 10–31 kg the stopping voltage if the source light is changed h = Planck constant = 6.6 × 10–34 Js with another source of wavelength of 474.6 nm? kB = Boltzmann constant = 1.38 × 10–23 JK–1] (JEE Main-2021) (JEE Main-2021) (1) 0.96 V (2) 1.25 V (1) 6.26 nm (2) 8.46 nm (3) 0.24 V (4) 1.5 V (3) 2.26 nm (4) 3.25 nm 71. X different wavelengths may be observed in the 76. The momentum of an electron revolving in nth orbit spectrum from a hydrogen sample if the atoms are is given by: (Symbols have their usual meanings) exited to states with principal quantum number n = 6? (JEE Main-2022) The value of X is _______. (JEE Main-2021) nh nh (1) (2) 2r 2r 72. A moving proton and electron have the same nh r (3) (4) de-Broglie wavelength. If K and P denote the K.E. 2 nh and momentum respectively. Then choose the correct option: (JEE Main-2021) 77. The magnetic moment of an electron (e) revolving in (1) KP < Ke and PP = Pe an orbit around nucleus with an orbital angular (2) KP = Ke and PP = Pe momentum is given by: (JEE Main-2022) (3) KP < Ke and PP < Pe eL eL (4) KP > Ke and PP = Pe (1) L = (2) L = − 2m 2m eL 2eL 73. A free electron of 2.6 eV energy collides with a (3) L = − (4) L = H+ ion. This results in the formation of a hydrogen m m atom in the first excited state and a photon is released. Find the frequency of the emitted photon. 78. Hydrogen atom from excited state comes to the (h = 6.6 × 10–34 Js) (JEE Main-2021) ground by emitting a photon of wavelength λ. The 16 (1) 1.45 × 10 MHz value of principal quantum number ‘n’ of the excited (2) 0.19 × 1015 MHz state will be: (JEE Main-2022) (3) 1.45 × 109 MHz R R (1) (2) (4) 9.0 × 1027 MHz  −1 R − 1  R2 74. Consider two separate ideal gases of electrons and (3) (4) protons having same number of particles. The R − 1 R − 1 temperature of both the gases are same. The ratio of the uncertainty in determining the position of an 79. In a hydrogen spectrum, λ be the wavelength of first electron to that of a proton is proportional to :- (JEE Main-2021) transition line of Lyman series. The wavelength  mp  3/2 me difference will be “aλ” between the wavelength of 3rd (1)   (2)  me  mp transition line of Paschen series and that of 2nd mp mp transition line of Balmer Series where a =______ (3) (4) me me (JEE Main-2022)  9 80. A nucleus of mass M at rest splits into two parts 85. A metal exposed to light of wavelength 800 nm and M' 2M ' emits photoelectrons with a certain kinetic energy. having masses and ( M '  M ). The ratio of 3 3 The maximum kinetic energy of photo-electron de Broglie wavelength of two parts will be: doubles when light of wavelength 500 nm is used. (JEE Main-2022) The work function of the metal is (1) 1 : 2 (2) 2 : 1 (3) 1 : 1 (4) 2 : 3 (take hc = 1230 eV-nm) (JEE Main-2022) (1) 1.537 eV (2) 2.46 eV 81. Mass numbers of two nuclei are in the ratio of 4 : 3. (3) 0.615 eV (4) 1.23 eV Their nuclear densities will be the ratio of (JEE Main-2022) 1 86. The ratio of de-Broglie wavelengths of proton and 3 3 deuteron accelerated by potential VP and Vd is 1: 2. (1) 4 : 3 (2)   4 Then the ratio of VP to Vd will be (JEE Main-2022) 1 2 :1 (1) 1 : 1 (2)  4 3 (3) 2 : 1 (4) 4 : 1 (3) 1 : 1 (4)   3 87. A parallel beam of light of wavelength 900 nm and 82. An electron (mass m) with an initial velocity intensity 100 Wm–2 is incident on a surface v = v0iˆ ( v0  0) is moving in an electric field perpendicular to the beam. The number of photons crossing 1 cm2 area perpendicular to the beam is one E = – E0iˆ ( E0  0) where E0 is constant. If at t = 0 de second is : (JEE Main-2022) h (1) 3 × 10 16 (2) 4.5 × 10 16 Broglie wavelength is 0 = , then its de Broglie mv0 (3) 4.5 × 1017 (4) 4.5 × 1020 wavelength after time t is given by (JEE Main-2022)  eE t  88. Two streams of photons, possessing energies to five (1) λ0 (2) 0 1 + 0   mv0  and ten times the work function of metal are incident 0 on the metal surface successively. The ratio of the (3) λ0t (4) maximum velocities of the photoelectron emitted, in  eE0t  1 +  the two cases respectively, will be (JEE Main-2022)  mv0  (1) 1 : 2 (2) 1 : 3 83. Find the ratio of energies of photons produced due to (3) 2 : 3 (4) 3 : 2 transition of an election of hydrogen atom from its (i) second permitted energy level to the first level, and (ii) the highest permitted energy level to the first 89. The kinetic energy of emitted electron is E when the permitted level. (JEE Main-2022) light incident on the metal has wavelength λ. To (1) 3 : 4 (2) 4 : 3 double the kinetic energy, the incident light must (3) 1 : 4 (4) 4 : 1 have wavelength: (JEE Main-2022) 84. Read the following statements: hc hc (1) Volume of the nucleus is directly proportional to (1) (2) the mass number. E − hc E + hc (2) Volume of the nucleus is independent of mass hc hc number. (3) (4) E + hc E − hc (3) Density of the nucleus is directly proportional to the mass number. (4) Density of the nucleus is directly proportional to 90. An α particle and a proton are accelerated from rest the cube root of the mass number. (5) Density of the nucleus is independent of the through the same potential difference. The ratio of mass number. linear momenta acquired by above two particles will Choose the correct option from the following options. be : (JEE Main-2022) (JEE Main-2022) (1) (1) and (4) only. (1) 2 :1 (2) 2 2 :1 (2) (1) and (5) only. (3) (2) and (3) only. (3) 4 2 :1 (4) 8:1 (4) (1) and (3) only  10 91. Two lighter nuclei combine to form a comparative 98. The light of two different frequencies whose photons heavier nucleus by the relation given below: have energies 3.8 eV and 1.4 eV respectively, 1 X + 1 X = 2Y. 2 2 4 illuminate a metallic surface whose work function is The binding energies per nucleon 12 X and 12 Y are 0.6 eV successively. The ratio of maximum speeds of 1.1 MeV and 7.6 MeV respectively. The energy emitted electrons for the two frequencies respectively released in this process is ______.MeV will be: (JEE Main-2022) (JEE Main-2022) (1) 1 : 1 (2) 2 : 1 (3) 4 : 1 (4) 1 : 4 92. In Bohr’s atomic model of hydrogen, let K.P and E are the kinetic energy, potential energy and total 99. Given below are two statements :- energy of the electron respectively. Choose the Statement I: Davission-Germer experiment correct option when the electron undergoes transition establishes the wave nature of electrons. to a higher level: (JEE Main-2022) (1) All K.P and E increase. Statement II: If electrons have wave nature, they can (2) K decreases. P and E increase interference and show diffraction. (3) P decreases. K and E increase. In the light of the above statements choose the correct (4) K increases. P and E decrease answer from the options given below:- (JEE Main-2022) 93. The ratio for the speed of the electron in the 3rd orbit (1) Both Statement I and Statement II are true of He+ to the speed of the electron in the 3rd orbit of (2) Both statement and Statement II are false. hydrogen atom will be :- (JEE Main-2022) (3) Statement I is true but Statement II is false (1) 1 : 1 (2) 1 : 2 (3) 4 : 1 (4) 2 : 1 (4) Statement I is false but Statement II is true 94. A hydrogen atom is in ground state absorbs 10.2 eV 100. A proton, a neutron, an electron and an α-particle of energy. The angular momentum of electron of the have same energy. If λP, λn, λe and λα are the hydrogen atom will increase by the value of: de-Broglie’s wavelength of proton, neutron, electron (Given , Plank’s constant = 6.6 × 10–34 Js) and α particle respectively, then choose the correct (JEE Main-2022) relation from the following: (JEE Main-2022) (1) 2.10 × 10–34 Js (2) 1.05 × 10–34 Js (1) λP = λn > λe > λα (3) 3.15 × 10–34 Js (4) 4.2 × 10–34 Js (2) λα < λn < λp < λe (3) λe < λp = λn > λα 95. A beam of monochromatic light is used to excite the (4) λe = λp = λn = λα electron in Li++ from the first orbit to the third orbit. The wavelength of monochromatic light is found to 101. An electron with speed v and a photon with speed c be x × 10–10 m. The value of x is____ have the same de-Broglie wavelength. If the kinetic [Given hc = 1242 eV nm] (JEE Main-2022) energy and momentum of electron are Ee and Pe and that of photon are Eph and Pph respectively. Which of 96. d1 and d2 are the impact parameters the following is correct ? (JEE Main-2022) Ee 2c Ee v corresponding to scattering angles 60° and 90° (1) = (2) = respectively, when an α particle is approaching a gold E ph v E ph 2c nucleus. For d1 = xd2, the value of x will be _____. Pe 2c Pe v (JEE Main-2022) (3) = (4) = Pph v Pph 2c 97. When light of frequency twice the threshold frequency is incident on the metal plate, the 102. The stopping potential for photoelectrons emitted maximum velocity of emitted election is v1. When the from a surface illuminated by light of wavelength frequency of incident radiation is increased to five 6630Å is 0.42 V. If the threshold frequency is times the threshold value, the maximum velocity of x × 1013/s, where x is ______ (nearest integer) emitted electron becomes v2. If v2 = x v1, the value of (Given, speed light = 3 × 108 m/s, Planck’s x will be ________. (JEE Main-2022) constant = 6.63 × 10–34 Js) (JEE Main-2022)  11 103. An α particle and a carbon 12 atom has same kinetic 107. Given below are two statements: One is labelled as energy K. the ratio of their de-Broglie wavelength Assertion A and other is labelled as Reason R. (λa : λC12) is : (JEE Main-2022) Assertion A : The photoelectric effect does not take place, if the energy of the incident radiation is less (1) 1: 3 (2) 3 :1 than the work function of a metal. (3) 3 : 1 (4) 2 : 3 Reason R : Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal. 104. Given below are two statements: In the light of the above statements, choose the most Statement I: In hydrogen atom, the frequency of appropriate answer from the options given below. radiation emitted when an electron jumps from lower (JEE Main-2022) energy orbit (E1) to higher energy orbit (E2), is given (1) Both A and R are correct and R is the correct explanation of A as hf = E1 – E2. (2) Both A and r are correct but R is not the correct Statement II: the jumping of electron from higher explanation of A energy orbit (E2) to lower energy orbit (E1) is (3) A is correct but R is not correct associated with frequency of radiation given as (4) A is not correct but R is correct f = (E2 – E1)/h. This condition is Bohr’s frequency condition. 108. The electric filed at the point associated with a light In the light of the above statements, choose the wave is given by correct answer from the options given below: E = 200[sin(6 × 1015)t + sin(9 × 1015)t]C = Vm−1 If (JEE Main-2022) this light falls on a metal surface having a work (1) Both Statement I and Statement II are true function of 2.50 eV, the maximum kinetic energy of (2) Both Statement I and Statement II are false the photoelectrons will be: (3) Statement I is correct but Statement II is false Given: h = 4.14 × 10–15 eVs (JEE Main-2022) (4) Statement I is incorrect but Statement II is true. (1) 1.90 eV (2) 3.27 eV (3) 3.60 eV (4) 3.42 eV 105. The de-Broglie wavelength for an electron and a photon are λe and λP respectively. For the same 109. Nucleus A is having mass number 220 and its binding energy per nucleon is 5.6 MeV. It splits in two kinetic energy of electron and photon. Which of the fragments ‘B’ and ‘C’ of mass numbers 105 and 115. following presents the correct relation between the The binding energy of nucleons in ‘B’ is 6.4 MeV per de-Broglie wavelength of two? (JEE Main-2022) nucleon. The energy Q released per fission will be: (1)  p  e2 (2)  p  e (JEE Main-2022) (1) 0.8 MeV (2) 275 MeV 1 (3) 220 MeV (4) 176 MeV (3)  p  e (4)  p  e 110. The energy released per fission of nucleus of 240X is 200 MeV. The energy released if all the atoms in 106. Let K1 and K2 be the maximum kinetic energies of 120 g of pure 240X undergo fission is __×1025 MeV. photo-electrons emitted when two monochromatic (Given NA = 6 × 1023) (24 January 2023 - Shift 2) beams of wavelength λ1 and λ2, respectively are incident on a metallic surface. If λ1 = 3λ2 then : (JEE Main-2022) 111. The ratio of the density of oxygen nucleus ( O ) and 16 8 (1) K2 K1  (2) K 2  K2 helium nucleus ( 4 2 He ) is _____. 3 3 (25 January 2023 - Shift 1) K K (3) K1 = 2 (4) K 2 = 1 (1) 4 : 1 (2) 8 : 1 3 3 (3) 1 : 1 (4) 2 : 1  12 92 A →90 B +2 D+Q 112. Given below are two statements: one is labelled as 116. 238 234 4 Assertion A and the other is labelled as Reason R. In the given nuclear reaction, the approximate Assertion A: The nuclear density of nuclides amount of energy released will be: [Given, mass of 10 6 56 20 209 5 B, 3 Li, 26 Fe, 10 Ne and 83 Bi can be arranged as −2 92 A = 238.05079  931.5MeVc 238 , mass of Bi N  Fe N  Ne N  BN  Li N. 90 B = 234.04363  931.5MeVc , 234 –2 mass of Reason R: The radius R of nucleus is related to its −2 2 D = 4.00260  931.5MeVc ] (13 April 2023 - Shift 1) 4 1 mass number A as R = R0 A3 , where R0 is a constant. (1) 3.82MeV (2) 5.9MeV In the light of the above statement, choose the correct (3) 2.12MeV (4) 4.25MeV answer from the options given below : (30 January 2023 - Shift 2) 117. Given below are two statements: one is labelled as (1) Both A and R are true and R is the correct Assertion A and the other is labelled as Reason R explanation of A Assertion A : The binding energy per nucleon is (2) A is false but R is true practically independent of the atomic number for (3) A is true but R is false nuclei of mass number in the range 30 to 170. (4) Both A and R are true but R is NOT the correct Reason R : Nuclear force is short ranged. explanation of A In the light of the above statements, choose the correct answer from the options given below. 113. A free neutron decays into a proton but a free proton (13 April 2023 - Shift 2) does not decay into neutron. This is because (1) A is false but R is true (31 January 2023 - Shift 1) (2) Both A and R are true and R is the correct (1) neutron is an uncharged particle explanation of A (2) proton is a charged particle (3) Both A and R are true but R is NOT the correct (3) neutron is a composite particle made of a proton and an electron explanation of A (4) neutron has larger rest mass than proton (4) A is true but R is false. 114. A nucleus with mass number 242 and binding energy 118. From the photoelectric effect experiment, following per nucleon as 7.6MeV breaks into two fragment observations are made. Identify which of these are each with mass number 121. If each fragment nucleus correct has binding energy per nucleon as 8.1MeV, the total A. The stopping potential depends only on the work gain in binding energy is _________MeV. function of the metal. (08 April 2023 - Shift 1) B. The saturation current increases as the intensity of incident light increases. 115. A common example of alpha decay is C. The maximum kinetic energy of a photo electron 238 92U → 234 90Th +2 He + Q 4 depends on the intensity of the incident light. Given: D. Photoelectric effect can be explained using wave theory of light. 238 92U = 238.05060u Choose the correct answer from the options given 90Th = 234.04360u 234 below: (24 January 2023 - Shift 1) MeV (1) B, C only 2 He = 4.00260 u and 1u = 931.5 2 c2 (2) A, C, D only The energy released (Q) during the alpha decay of (3) B only 238 (4) A, B, D only 92U is _______MeV. (12 April 2023 - Shift 1)  13 119. Electron beam used in an electron microscope, when 123. A point source of light is placed at the centre of accelerated by a voltage of 20 kV. has a de-Broglie curvature of a hemispherical surface. The source wavelength of λ0. If the voltage is increased to 40kV. emits a power of 24W The radius of curvature of then the de-Broglie wavelength associated with the hemisphere is 10cm and the inner surface is electron beam would be: (25 January 2023 - Shift 1) completely reflecting. The force on the hemisphere (1) 3λ0 (2) 9λ0 due to the light falling on it is _______×10–8 N. 0 0 (30 January 2023 - Shift 1) (3) (4) 2 2 124. An electron accelerated through a potential difference V1 has a de-Broglie wavelength of λ. When the 120. Given below are two statements: potential is changed to V2, its de-Broglie wavelength Statement I : Stopping potential in photoelectric effect does not depend on the power of the light V  increases by 50%. The value of  1  is equal to: source.  V2  Statement II : For a given metal, the maximum (30 January 2023 - Shift 2) kinetic energy of the photoelectron depends on the (1) 3 (2) 9/4 wavelength of the incident light. (3) 3/2 (4) 4 In the light of above statements, choose the most appropriate answer from the options given below. 125. If a source of electromagnetic radiation having power (25 January 2023 - Shift 2) 15kW produces 1016 photons per second, the (1) Statement I is incorrect but statement II is radiation belongs to a part of spectrum is. correct (Take Planck constant h = 6 × 10–34 Js) (2) Both Statement I and Statement II are incorrect (31 January 2023 - Shift 1) (3) Statement I is correct but statement II is (1) Micro waves incorrect (2) Ultraviolet rays (4) Both statement I and statement II are correct (3) Gamma rays (4) Radio waves 121. The threshold wavelength for photoelectric emission from a material is 5500Å. Photoelectrons will be 126. If the two metals A and B are exposed to radiation of emitted, when this material is illuminated with wavelength 350nm. The work functions of metals A monochromatic radiation from a and B are 4.8eV and 2.2eV. Then choose the correct A. 75 W infra-red lamp option. (31 January 2023 - Shift 2) B. 10 W infra-red lamp C. 75 W ultra-violet lamp (1) Metal B will not emit photo-electrons D. 10 W ultra-violet lamp (2) Both metals A and B will emit photo-electrons Choose the correct answer from the options given (3) Both metals A and B will not emit below: (29 January 2023 - Shift 1) photoelectrons (1) B and C only (2) A and D only (4) Metal A will not emit photo-electrons (3) C only (4) C and D only 127. A proton moving with one tenth of velocity of light 122. The ratio of de-Broglie wavelength of an -particle has a certain de Broglie wavelength of λ. An alpha and a proton accelerated from rest by the same particle having certain kinetic energy has the same 1 de-Brogle wavelength λ. The ratio of kinetic energy potential is , the value of m is __________. m of proton and that of alpha particle is: (29 January 2023 - Shift 2) (01 February 2023 - Shift 1) (1) 4 (2) 16 (1) 2 : 1 (2) 4 : 1 (3) 8 (4) 2 (3) 1 : 2 (4) 1 : 4  14 128. The threshold frequency of metal is f0. When the light 133. The de Broglie wavelength of a molecule in a gas at of frequency 2f0 is incident on the metal plate, the room temperature (300K) is λ1. If the temperature of maximum velocity of photoelectron is v1. When the the gas is increased to 600K, then the de Broglie wavelength of the same gas molecule becomes frequency of incident radiation is increased to 5f0. the (10 April 2023 - Shift 1) maximum velocity of photoelectrons emitted is v2. 1 The ratio of v1 to v2 is: (01 February 2023 - Shift 2) (1) 1 (2) 21 2 v 1 v 1 1 (1) 1 = (2) 1 = (3) 1 (4) 21 v2 2 v2 8 2 v1 1 v1 1 (3) = (4) = 134. The variation of stopping potential (V0) as a function v2 16 v2 4 of the frequency (ν) of the incident light for a metal is shown in figure. The work function of the surface 129. The kinetic energy of an electron, α-particle and a is. (10 April 2023 - Shift 2) proton are given as 4K, 2K and K respectively. The de-Broglie wavelength associated with electron (λe), α-particle (λα) and the proton (λp) are as follows: (06 April 2023 - Shift 1) (1) λα = λp > λe (2) λα < λp < λe (3) λα = λp < λe (4) λα > λp > λe 130. The work functions of Aluminium and Gold are 4.1eV and 5.1eV respectively. The ratio of the slope of the stopping potential versus frequency plot for Gold to that of Aluminium is _______. (1) 2.98 eV (2) 2.07 eV (06 April 2023 - Shift 2) (3) 1.36 eV (4) 18.6 eV (1) 1.24 (2) 2 (3) 1 (4) 1.5 135. A metallic surface is illuminated with radiation of 131. Proton (P) and electron (e) will have same de-Broglie wavelength λ, the stopping potential is V0. If the same wavelength when the ratio of their momentum is surface is illuminated with radiation of wavelength (assume, mp = 1849me). (08 April 2023 - Shift 1) V0 (1) 1 :1 (2) 1 :1849 2λ, the stopping potential becomes. The (3) 1 : 43 (4) 43 :1 4 threshold wavelength for this metallic surface will 132. In photoelectric effect be ________. (11 April 2023 - Shift 1) A. The photocurrent is proportional to the intensity (1) 3 (2) 4 of the incident radiation. 3  B. Maximum kinetic energy with which (3)  (4) photoelectrons are emitted depends on the 2 4 intensity of incident light. C. Max K.E. with which photoelectrons are emitted 136. The ratio of the de-Broglie wavelengths of proton and depends on the frequency of incident light. electron having same kinetic energy: D. The emission of photoelectrons require a (Assume mp = me × 1849) (11 April 2023 - Shift 2) minimum threshold intensity of incident (1) 1 : 43 (2) 1 : 30 radiation. (3) 1 : 62 (4) 2 : 43 E. Max K.E. of the photoelectrons is independent of the frequency of the incident light. 137. A proton and an α-particle are accelerated from rest Choose the correct answer from the options given by 2V and 4V potentials, respectively. The ratio of below: their de-Broglie wavelength is : (12 April 2023 - Shift 1) (08 April 2023 - Shift 2) (1) A and B only (2) A and E only (1) 8 : 1 (2) 2 : 1 (3) A and C only (4) B and C only (3) 4 : 1 (4) 16 : 1  15 138. The difference between threshold wavelengths for 144. For hydrogen atom, λ1 and λ2 are the wavelengths two metal surfaces A and B having work function corresponding to the transitions 1 and 2 respectively ϕA = 9eV and ϕB = 4.5eV in nm is: x {Given, hc = 1242eVnm} (13 April 2023 - Shift 1) as shown in figure. The ratio of λ1 and λ2 is. The 32 (1) 540 (2) 276 (3) 264 (4) 138 value of x is _________. (31 January 2023 - Shift 1) 139. The de Broglie wavelength of an electron having kinetic energy E is λ. If the kinetic energy of electron E becomes , then its de-Broglie wavelength will be: 4 (15 April 2023 - Shift 1)  145. The radius of electron's second stationary orbit in (1) 2 (2) 2 Bohr's atom is R. The radius of 3rd orbit will be  ________. (31 January 2023 - Shift 2) (3) (4) 2 (1) R/3 (2) 2.25R 2 (3) 3R (4) 9R 140. A photon is emitted in transition from n = 4 to n = 1 level in hydrogen atom. The corresponding 146. If the binding energy of ground state electron in a wavelength for this transition is. hydrogen atom is 13.6eV, then, the energy required (given, h = 4 × 10–15 e Vs): (24 January 2023 - Shift 2) to remove the electron from the second excited state (1) 94.1 nm (2) 941 nm of Li2+ will be: x × 10–1 eV. The value of x is _____. (3) 97.4 nm (4) 99.3 nm (31 January 2023 - Shift 2) 141. The wavelength of the radiation emitted is λ0 when an 147. The mass of proton, neutron and helium nucleus are electron jumps from the second excited state to the respectively 1.0073u, 1.0087u and 4.0015u. The first excited state of hydrogen atom. If the electron binding energy of helium nucleus is _______. jumps from the third excited state to the second orbit (01 February 2023 - Shift 1) of the hydrogen atom, the wavelength of the radiation (1) 14.2MeV (2) 28.4MeV 20 emitted will be 0. The value of x is _______. (3) 56.8MeV (4) 7.1MeV x (25 January 2023 - Shift 1) 148. A light of energy 12.75eV is incident on a hydrogen 142. The energy levels of an atom is shown is figure. atom in its ground state. The atom absorbs the Which one of these transitions will result in the radiation and reaches to one of its excited states. The emission of a photon of wavelength 124.1 nm? angular momentum of the atom in the excited state is Given (h = 6.62 × 10–34 Js) (25 January 2023 - Shift 2) x  10−17 eVs. The value of x is ______.  (use h = 4.14 × 10–15 eVs, c = 3 × 108 ms–1). (01 February 2023 - Shift 1) 149. An electron of a hydrogen like atom, having Z = 4, (1) B (2) A jumps from 4th energy state to 2nd energy state, The (3) C (4) D energy released in this process, will be: 143. Speed of an electron in Bohr's 7th orbit for Hydrogen (Given Rch = 13.6eV) atom is 3.6 × 106 m/s. The corresponding speed of the Where R = Rydberg constant electron in 3rd orbit, in m/s is : c = Speed of light in vacuum (30 January 2023 - Shift 1) h = Planck's constant (01 February 2023 - Shift 1) (1) (1.8 × 10 )6 (2) (7.5 × 106) (1) 13.6eV (2) 10.5eV (3) (3.6 × 106) (4) (8.4 × 106) (3) 3.4eV (4) 40.8eV  16 150. Nucleus a having Z = 17 and equal number of protons 157. The energy of He+ ion in its first state is, (The ground and neutrons has 1.2 MeV binding energy per state energy for the Hydrogen atom –13.6 eV): nucleon. (11 April 2023 - Shift 2) Another nucleus B of Z = 12 has total 26 nucleons and (1) −27. 2 eV (2) −3. 4 eV 1.8MeV binding energy per nucleons. (3) −13. 6 eV (4) −54. 4 eV The difference of binding energy of B and A will be ______ MeV. (01 February 2023 - Shift 2) 158. A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. The number of 151. The energy levels of an hydrogen atom are shown spectral lines emitted will be: (12 April 2023 - Shift 1) below. The transition corresponding to emission of (1) 1 (2) 4 shortest wavelength is ______. (06 April 2023 - Shift 1) (3) 2 (4) 3 159. The radius of 2nd orbit of He+ of Bohr's model is r1 and that of fourth orbit of Be3+ is represented as r2. r Now the ratio 2 is x : 1. The value of x is ______. r1 (1) D (2) A (13 April 2023 - Shift 1) (3) B (4) C 160. An atom absorbs a photon of wavelength 500 nm and emits another photon of wavelength 600 nm. The net 152. The radius of fifth orbit of Li++ is _______ × 10–12 m. energy absorbed by the atom in this process is Take: radius of hydrogen atom = 0.51Å. (06 April 2023 - Shift 1) n × 10–4 eV. The value of n is [Assume the atom to be stationary during the absorption and emission 153. The ratio of wavelength of spectral lines Hα and Hβ in process]. x (Take h = 6.6 × 10–34 Js and c = 3 × 108 ms–1). the Balmer series is. The value of x is _______. (13 April 2023 - Shift 2) 20 (08 April 2023 - Shift 2) 161. As per given figure A, B and C are the first, second 154. The angular momentum for the electron in Bohr's and third excited energy levels of hydrogen atom orbit is L. If the electron is assumed to revolve in respectively. If the ratio of the two wavelengths second orbit of hydrogen atom, then the change in angular momentum will be ______.  1  7  i.e.  is , then the value of n will be ______. (10 April 2023 - Shift 1)  2  4n (1) Zero (2) 2L (13 April 2023 - Shift 2) (3) L (4) L/2 162. The minimum energy required by a hydrogen atom in ground state to emit radiation in Balmer series is 155. If 917Å be the lowest wavelength of Lyman series nearly: (01 Feb. 2024 - Shift 1) then the lowest wavelength of Balmer series will (1) 1.5 ev (2) 13.6 ev be ______Å. (10 April 2023 - Shift 2) (3) 1.9 ev (4) 12.1 ev 156. A monochromatic light is incident on a hydrogen 163. A particular hydrogen - like ion emits the radiation of frequency 3 × 1015 Hz when it makes transition from sample in ground state. Hydrogen atoms absorb a n = 2 to n = 1. The frequency of radiation emitted in fraction of light and subsequently emit radiation of 𝑥 transition from n = 3 to n = 1 is × 1015 Hz, when six different wavelengths. The frequency of incident 9 x = _____. (01 Feb. 2024 - Shift 2) light is x × 1015 Hz. The value of x is _________. (Given h = 4.25 × 10–15 eVs) (11 April 2023 - Shift 1)  17 164. The radius of third stationary orbit of electron for 169. The ratio of the magnitude of the kinetic energy to the Bohr's atom is R. The radius of fourth stationary orbit potential energy of an electron in the 5th excited state will be: (27 Jan. 2024 - Shift 1) of a hydrogen atom is: (30 Jan. 2024 - Shift 1) 4 16 (1) 4 (2) 1/4 (1) R (2) R 3 9 (3) 1/2 (4) 1 3 9 (3) R (4) R 170. A electron of hydrogen atom on an excited state is 4 16 having energy En = –0.85 eV. The maximum number 165. If Rydberg's constant is R, the longest wavelength of of allowed transitions to lower energy level  is ______. (30 Jan. 2024 - Shift 1) radiation in Paschen series will be where 7R 171. An electron revolving in nth Bohr orbit has magnetic  = _____. (27 Jan. 2024 - Shift 2) moment μn. If μnαnx, the value of x is: (30 Jan. 2024 - Shift 2) 166. When a hydrogen atom going from n = 2 to n = 1 (1) 2 (2) 1 x (3) 3 (4) 0 emits a photon, its recoil speed is m/s. 5 172. The mass defect in a particular reaction is 0.4 g. The Where x = ______. (Use : mass of hydrogen atom amount of energy liberated is n × 107 kWh, where = 1.6 × 10–27 kg). (29 Jan. 2024 - Shift 1) n = ________. (speed of light = 3 × 108 m/s) (31 Jan. 2024 - Shift 1) 167. Given below are two statements: 173. A hydrogen atom changes its state from n = 3 to Statement I: Most of the mass of the atom and all its n = 2. Due to recoil, the percentage change in the positive charge are concentrated in a tiny nucleus and wave length of emitted light is approximately the electrons revolve around it, is Rutherford's model. 1 × 10–n. The value of n is. [Given Rhc =13.6eV, Statement II: An atom is a spherical cloud of hc = 1242eVnm, h = 6.6 × 10−34 J s mass of the positive charges with electrons embedded in it, is a hydrogenatom = 1.6 × 10−27 kg] special case of Rutherford's model. (04 April 2024 - Shift 1) In the light of the above statements, choose the most appropriate from the options given below. 174. According to Bohr's theory, the moment of (29 Jan. 2024 - Shift 2) momentum of an electron revolving in 4th orbit of (1) Both statement I and statement II are false hydrogen atom is: (04 April 2024 - Shift 2) (2) Statement I is false but statement II is true h h (3) Statement I is true but statement II is false (1) (2)  2 (4) Both statement I and statement II are true h h (3) 8 (4) 2   168. Hydrogen atom is bombarded with electrons accelerated through a potential different of V, whi