Content text 24. Atomic Physics - Medium-1.pdf
1. The first model of atom in 1898 was proposed by (a) Ernst Rutherford (b) Alert Einstein (c) J.J. Thomson (d) Niels Bohr 2. The graph of the total number of − scattered at different angles in a given interval of time for − scattering in the Geiger-Marsden experiment is given by (a) (b) (c) (d) 3. Rutherford’s experiments suggested that the size of the nucleus is about (a) 10 m to10 m −14 −12 (b) 10 m to10 m −15 −13 (c) 10 m to10 m −15 −14 (d) 15 12 10 m to10 − − 4. In the Geiger-Marsden scattering experiment the number of scattered particles detected are maximum and minimum at the scattering angles respectively at (a) 0° and 180° (b) 180° and 0° (c) 90° and 180° (d) 45° and 90° 5. In the Geiger-Marsden scattering experiment, in case of head- on collision the impact parameter should be (a) Maximum (b) Minimum (c) Infinite (d) Zero 6. In an atom the ratio of radius of orbit of electron to the radius of nucleus is (a) 3 10 (b) 4 10 (c) 5 10 (d) 6 10 7. The relation between the orbit radius and the electron velocity for a dynamically stable orbit in a hydrogen atom is (where, all notations have their usual meanings) (a) me r 4 v 2 0 = (b) 4 v e r 0 2 = (c) 4 mr e v 0 2 = (d) 4 m ve r 0 2 = 8. In Geiger-Marsden scattering experiment, the trajectory traced by an − depends on (a) Number of collision (b) Number of scattered − particles (c) Impact parameter (d) None of these 9. In a Geiger-Marsden experiment. Find the distance of closest approach to the nucleus of a 7.7 MeV −before it comes momentarily to rest and reverses its direction. (Z for gold nucleus = 79) (a) 10 fm (b) 20 fm (c) 30 fm (d) 40 fm 10. The relationship between kinetic energy (K) and potential energy (U) of electron moving in a orbit around the nucleus is (a) U = −K (b) U = −2K (c) U = −3K (d) K 2 1 U = − 11. The volume occupied by an atom is greater than the volume of the nucleus by a factor of about (a) 1 10 (b) 5 10 (c) 10 10 (d) 15 10 12. In a experiment on − particle scattering −particles, are directed towards a gold foil and detectors are placed in position P, Q and R. What is the distribution of −particles as recorded at P, Q and R? P Q R (a) All None None (b) None None All (c) A few Some Most (d) Most Some A few 13. When an atomic gas or vapour is excited at low pressure, by passing an electric current through it then (a) Emission spectrum is observed (b) Absorption spectrum is observed (c) Band spectrum is observed (d) Both (b) and (c) 14. The first spectral series was discovered by (a) Balmer (b) Lyman (c) Paschen (d) Pfund 15. The shortest wavelength in the Balmer series is (Take R 1.097 10 m ) 7 −1 = (a) 200 nm (b) 256.8 nm (c) 300 nm (d) 364.6 nm
16. Which of the following spectral series falls within the visible range of electromagnetic radiation? (a) Lyman series (b) Balmer series (c) Paschen series (d) Pfund series 17. In Balmer seris of emission spectrum of hydrogen, first four lines with different wavelength HHH and H are obtained. Which line has maximum frequency out of these? (a) Hα (b) Hβ (c) Hγ (d) H 18. The shortest wavelength present in the Paschen series of spectral lines is (a) 720 nm (b) 790 nm (c) 800 nm (d) 820 nm 19. The wavelength limit present in the Pfund series is (R 1.097 10 ms ) 7 −1 = (a) 1572 nm (b) 1898 nm (c) 2278 nm (d) 2535 nm 20. Hydrogen atom emits light when it changes from n = 5 energy level to n = 2 energy levle. Which colour of light would the atom emit? (a) Red (b) Yellow (c) Green (d) Violet 21. The wavelength of the first line of Lyman series is 1215 Å, the wavelength of first line of Balmer series will be (a) 4545 Å (b) 5295 Å (c) 6561 Å (d) 6750 Å 22. When an electron jumps from the fourth orbit to the Second orbit, one gets the (a) Second line of Paschen series (b) Second line of Balmer series (c) First line of Pfund series (d) Second line of Lyman series 23. The Balmer series for the H-atom can be observed (a) If we measure the frequencies of light emitted when an excited atom falls to the ground state (b) If we measure the frequencies of light emitted due to transitions between excited states and the first excited state. (c) In any transition in a H-atom (d) None of these 24. The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is (a) 3 (b) 4 (c) 1 (d) 2 25. The first line of the Lyman series in a hydrogen spectrum has a wavelength of 1210 Å. The corresponding line of a hydrogen- like atom of Z = 11 is equal to (a) 4000 Å (b) 100 Å (c) 40 Å (d) 10 Å 26. If 1 is the frequency of the series limit of Lyman series, 2 is the frequency of the first line of Lyman series and 3 is the frequency of the series limit of the Balmer sereis, then (a) 1 −2 = 3 (b) 1 = 2 −3 (c) 2 1 3 1 1 1 + = (d) 1 2 3 1 1 1 + = 27. If the wavelength of the first line of the Balmer series of hydrogen is 6561 Å, the wavelength of the second line of the series should be (a) 13122 Å (b) 3280 Å (c) 4860 Å (d) 2187 Å 28. If the wavelength of the first line of the Balmer series of hydrogen is 6561 Å, the wavelength of the second line of the series should be (a) 13122 Å (b) 3280 Å (c) 4860 Å (d) 2187 Å 29. The transition from the state n = 3 to n = 1 in a hydrogen like atom results in ultravoilet radiation. Infrarede radiation will be obtained in the transition from (a) 2 →1 (b) 3→2 (c) 4 → 2 (d) 4→3 30. The Bohr model of atoms (a) Assumes that the angular momentum of electrons is quantized. (b) Uses Einstein’s photoelectric equation. (c) Predicts continuous emission spectra for atoms. (d) Predicts the same emission spectra for all types of atoms. 31. In a hydrogen atom the total energy of electron is (a) 4 r e 0 2 (b) 4 r e 0 2 − (c) 8 r e 0 2 − (d) 8 r e 0 2 32. In which of the following systems will the radius of the first orbit (n = 1) be minimum? (a) Doubly ionized lithium (b) Singly ionized helium (c) Deuterium atom (d) Hydrogen atom 33. The moment of momentum for an electron in second orbit of hydrogen atom as per Bohr’s model is (a) h (b) 2h (c) 2h (d) h
34. According to second postulate of Bohr model, the angular momentum ( ) Ln of nth possible orbit of hydrogen atom is given by (a) 2 n h (b) 2 nh (c) h 2n (d) nh 2 35. Which of the following statements is true for hydrogen atom? (a) Angular moment n 1 (b) Linear moment n 1 (c) Radius n 1 (d) Energy n 1 36. The total energy (E ) n of the electron in the stationary states in the nth orbit of the hydrogen atom is (a) eV n −13.6 (b) eV n 13.6 2 − (c) eV n −136 (d) eV n 136 2 − 37. The radius of nth orbit n r in terms of Bohr radius ( ) 0 a for a hydrogen atom is given by the relation (a) na 0 (b) 0 n a (c) 0 2 n a (d) 0 3 n a 38. In the Bohr model of the hydrogen atom, the lowest orbit corresponds to (a) Infinite energy (b) Maximum energy (c) Minimum energy (d) Zero energy 39. The value of ionisation energy of the hydrogen atom is (a) 3.4 V (b) 10.4 eV (c) 12.09 eV (d) 13.6 eV 40. Energy is abosrbed in the hydrogen atom giving absorption spectra when transtion takes place from (a) n =1→n' where n'1 (b) n = 2 →1 (c) n'→n (d) n → n' = 41. If n is the orbit number of the electron in a hydrogen atom, the correct statement among the following is (a) Electron energy increases as n increases. (b) Hydrogen emits infrared rays for the electron transition from n = to n = 1. (c) Electron energy is zero for n = 1. (d) Electron energy vaires as 2 n 42. If 13.6 eV energy is requied to separate a hydrogen atom into a proton and an electron, then the orbital radius of electron in a hydrogen atom is (a) 5.3 10 m −11 (b) 4.3 10 m −11 (c) 6.3 10 m −11 (d) 7.3 10 m −11 43. Which of the following is not correct about Bohr model of the hydrogen atom? (a) An electron in an atom could revolve in certain stable orbits without the emission of radiant energy (b) Electron revolves around the nucleus only in those orbits for which angular momentum . 2 nh Ln = (c)When electron make a taransition from one of its stable orbit to lower orbit then a photon emitted with energy h E E . = f − i (d) Bohr model is applicable to all atoms. 44. If an electron is revolving in its Bohr orbit having Bohr radius of 0.529 Å, then the radius of third orbit is (a) 4234 nm (b) 4496 Å (c) 4.71 Å (d) 5125 nm 45. The energy required to excite an electron in hydrogen atom to its first excited state is (a) 8.5 eV (b) 10.2 Ev (c) 12.7 eV (d) 13.6 eV 46. A triply ionized beryllium ( ) 3+ Be has the same orbital radius as the ground state of hydrogen. Then the quantum state n of ( ) 3+ Be is (a) n = 1 (b) n = 2 (c) n = 3 (d) n = 4 47. In the question number 57, find the potential energy of electron (in Joule) in the given state. (a) 4.36 10 J −14 − (b) 4.36 10 J −16 − (c) 4.36 10 J −17 − (d) 4.36 10 J −18 − 48. If the radius of inner most electronic orbit of hydrogen atom is , 11 5.3 10− m then the radii of n = 2 orbit is (a) 1.12 Å (b) 2.12 Å (c) 3.22 Å (d) 4.54 Å 49. A hydrogen atom initially in the ground level absorbs a photon and is excited n = 4 level then the wavelength of photon is (a) 790 Å (b) 870 Å (c) 970 Å (d) 1070 Å 50. What is the frequency of photon in question number 60? (a) 3.1 10 Hz 15 (b) 3.1 10 Hz 18 (c) 9.1 10 Hz 15 (d) 9.1 10 Hz 18 51. If speed of electron in ground state energy level 2.2 10 ms , 6 −1 is then its speed in fourth excited state will be (a) 6 1 6.8 10 ms − (b) 5 1 8.8 10 ms − (c) 5 1 5.5 10 ms − (d) 6 1 5.5 10 ms − 52. If muonic hydrogen atom is an atom in which a negatively charged muon () of mass about 207me revolves around a
proton,then first Bohr radius of this atom is (r 0.53 10 m) 10 e − = (a) 2.56 10 m −10 (b) 2.56 10 m −11 (c) 2.56 10 m −12 (d) 2.56 10 m −13 53. In the question number 65, if ground state energy of electron is −13.6 eV then what is the ground state energy of muonic hydrogen atom? (a) 1.8 keV (b) −2.8 keV (c) −3.8 keV (d) 4.8 keV 54. An electron is revolving in the nth orbit of radius 4.2 Å, then the value of n is (r 0.529Å) 1 = (a) 4 (b) 5 (c) 6 (d) 3 55. Which of the following postulates of the Bohr model led to the quantization of energy of the hydrogen atom? (a) The electron goes around the nucleus is circular orbits. (b) The angular momentum of the electron can only be an integral multiple of h / 2 (c) The magnitude of the linear momentum of the electron is quantized. (d) Quantization of energy is itself a postulate of the Bohr model. 56. An electron in the ground state of hydrogen atom is revolving in anticlokwise direction in circular orbit of radius R. The orbital magneitc dipole moment of the electron will be. (a) 4 m eh (b) 2 m eh (c) 4 m eh2 (d) 4 m eh2 57. The electric current I created by the electron in the ground state of H atom using Bohr model in terms of Bohr radius (a ) 0 and velocity of electron in first orbit 0 v is (a) 0 0 2 a ev (b) 0 ev 2a (c) v0 2a (d) 2 a v0 58. If E is the energy of orbit of hydrogen atom the energy of nth orbit of He atom will be (a) E (b) 2E (c) 3E (d) 4E 59. Positronium is like a H atom with the proton replaced by positron (a positively charged antiparticle of the electron which is as massive as electron). The ground state energy of positronium would be (a) −3.4 eV (b) −5.2 eV (c) −6.8 eV (d) −10.2 eV 60. The minimum energy that must be given to a H atom in ground state so that it can emit an H . line in Balmer series is (a) 12.4 eV (b) 10.2 eV (c) 13.06 eV (d) 13.6 eV 61. In the question number 75, what would be the angular momentum of H photon if the angular momentum of the system is conserved (a) (b) 2 (c) 3 (d) 4 62. When an electron falls from a higher energy to a lower energy level the difference in the energies appears in the form of (a) Electromagnetic radiation only (b) Thermal radiation only (c) Both electromagnetic and thermal radiations (d) None these 63. The angular speed of the electron in the th n orbit of Bohr’s hydrogen atom is (a) Directly proportional to n (b) Inversely proportional to n (c) Inversely proportional to 2 n (d) Inversely proportional to 3 n 64. Let 2 2 0 4 n 8 n me E − = be the energy of the th n level of H-atom. If all the H-atoms are in the ground state and radiation of frequency (E2 − E1 )/h falls on it, then (a) It will not be absorbed at all (b) Some of atoms will move to the first excited state (c) All atoms will be excited to the n = 2 state (d) All atoms will make a transition to the n = 3 State 65. An ionised H-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state, (a) The electron would not move in circular orbits (b) The energy would be ( ) 4 2 times that of a H- Atom (c) The molecule will soon decay in to a proton and a H- atom (d) None of these 66. Energy E of hydrogen atom with principal quantum number n is given by eV. n 13.6 E 2 − = The energy of a photon ejected when the electron jumps from n = 3 state to n = 2 state of hydrogen is approximately (a) 1.5 eV (b) 0.85 eV (c) 3.4 eV (d) 1.9 eV 67. Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr’s atomic model? (a) 0.65 eV (b) 1.9 eV (c) 11.1 eV (d) 13.6 eV
Tiếng Việt