12 CHAPTER STRUCTURE OF ATOM 1. The spectrum of He is expected to be similar to that [1988] H Li + Na He + 2. The number of spherical nodes in 3p orbitals are [1988] one three none two 3. If r is the radius of the first orbit, the radius of nth orbit of H-atom is given by [1988] rn 2 rn r/n r 2 n 2 4. Which of the following statements do not form a part of Bohr s model of hydrogen atom? [1989] Energy of the electrons in the orbits are quantized The electron in the orbit nearest the nucleus has the lowest energy Electrons revolve in different orbits around the nucleus The position and velocity of the electrons in the orbit cannot be determined simultaneously. 5. Number of unpaired electrons in N 2+ is [1989] 2 0 1 3 6. The maximum number of electrons in a subshell is given by the expression [1989] 4l 2 4l + 2 2l + 2 2n 2 7. The total number of electrons that can be accommodated in all the orbitals having principal quantum number 2 and azimuthal quantum number 1 is [1990] 2 4 6 8 8. An ion has 18 electrons in the outermost shell, it is [1990] Cu + Th 4+ Cs + K + 9. In a given atom no two electrons can have the same values for all the four quantum numbers. This is called [1991] Hund s Rule Aufbau principle Uncertainty principle Pauli s Exclusion principle. 10. [1991] 2 6 0 14 11. The order of filling of electrons in the orbitals of an atom will be [1991] 3d, 4s, 4p, 4d, 5s 4s, 3d, 4p, 5s, 4d 5s, 4p, 3d, 4d, 5s 3d, 4p, 4s, 4d, 5s 12. The energy of an electron in the n the Bohr orbit of hydrogen atom is [1992]
13 13. Which of the following species has four lone pairs of electrons? [1993] I O Cl He 14. If ionization potential for hydrogen atom is 13.6 ev, then ionization potential for He + will be [1993] 54.4 ev 6.8 ev 13.6 ev 24.5 ev 15. [1994] 16. Which of the following is never true for cathode rays? [1994] They possess kinetic energy They are electromagnetic waves They produce heat They produce mechanical pressure. 17. The electron was shown experimentally to have wave properties by [1994] de Broglie Davisson and Germer N. Bohr Schrodinger. 18. 18 When an electron of charge e and mass m moves with a velocity v about the nuclear charge Ze is circular orbit of radius r, the potential energy of the electrons is given by [1994] Ze 2 /r -Ze 2 /r Ze 2 /2r mv 2 /r 19. In the photo-electron emission, the energy of the emitted electron is [1994] greater than the incident photon same as than of the incident photon smaller than the incident photon proportional to the intensity of incident photon. 20. If electron has spin quantum number + 2 / 1 and a magnetic quantum number -1, it cannot be present in [1994] d-orbital f-orbital p-orbital s-orbital. 21. [1995] 22. Uncertainty in position of an electron (mass = 9.1 10 28 g) moving with a velocity of 3 10 4 cm/s accurate upto % 0.001 will be (use h/4 π) in uncertainty expression where h = 6.626 10 27 erg-second) [1995] 1.93 cm 3.84 cm 5.76 cm 7.68 cm 23. The orbitals are called degenerate when [1996] they have the same wave functions they have the same wave functions but different energies
14 they have different wave functions but same energy they have the same energy 24. The momentum of a particle having a de Broglie wavelength of 10 17 metres is (Given h = 6.625 10 34 Js) [1996] 3.3125 10 7 kg ms 1 26.5 10 7 kg ms 1 6.625 10 17 kg ms 1 13.25 10 17 kg ms 1 25. The ion that is isoelectronic with CO is [1997] CN + O2 O2 + N2 26. [1998] 0.13 1.06 4.77 2.12 27. The position of both, an electron and a helium atom is known within 1.0 nm. Further the momentum of the electron is known within 5.0 10 26 kg ms. 1 The minimum uncertainty in the measurement of the momentum of the helium atom is [1998] 50 kg ms 1 80 kg ms 1 8.0 10 26 kg ms 1 5.0 10 26 kg ms 1 28. According to Bohr s theory the energy required for an electron in the Li 2+ ion to be emitted from n = 2 state is (given that the ground state ionization energy of hydrogen atom is 13.6 ev) [1999] 61.2 ev 13.6 ev 30.6 ev 10.2 ev 29. If the energy of a photon is given as: = 3.03 10 19 J then, the wavelength of the photon is: [2000] 6.56 nm 65.6 nm 656 nm 0.656 nm 30. Set of isoelectronic species is [2000] N2,CO2,CN -,O N,H2S,CO N2, CO, CN -, O2 +2 Ca,Mg,Cl 31. The following quantum numbers are possible for how many orbital n = 3, l = 2, m = +2? [2001] 1 3 2 4 32. Which of the following is isoelectronic? [2002] CO2, NO2 NO2, CO2 CN, CO SO2, CO2 33. In hydrogen atom, energy of first excited state is 3.4 ev. Find out KEof the same orbit of Hydrogen atom [2002] + 3.4 ev + 6.8 ev 13.6 ev + 13.6 ev 34. The value of Planck's constant is 6.63 10 34 Js. The velocity of light is 3.0 10 8 m s. 1 Which value is closest to the wavelength in nanometers of a quantum of light with frequency of 8 10 15 s 1? [2003] 3 10 7 2 10 25
15 5 10 18 4 10 1 35. The ions O 2, F, Na+, Mg 2+ and Al 3+ are isoelectronic. Their ionic radii show [2003] Adecrease from O 2 to F and then increase from Na+ to Al 3+ Asignificant increase from O 2 to Al 3+ Asignificant decrease from O 2 to Al 3+ An increase from O 2 to F and then decrease from Na + to Al 3+ 36. The frequency of radiation emitted when the electron falls from n = 4 to n = 1 in a hydrogen atom will be (Given ionization energy of H=2.18 10 18 J atom 1 and h = 6.625 10 34 Js) [2004] 37. The energy of second Bohr orbit of the hydrogen atom is 328 kjmol1; hence the energy of fourth Bohr orbit would be: [2005] 41 - kjmol - 1 82 - kjmol - 1 164 - kjmol - 1 1312 - kjmol - 1 38. Given: The mass of electron is 9.11 10 31 kg Plank constant is 6.626 10 34 Js, the uncertainty involved in the measurement of velocity within a distance of 0.1 A is [2006] 5.79 10 7 ms 1 5.79 10 8 ms 1 5.79 10 5 ms 1 5.79 10 6 ms 1 39. The orientation of an atomic orbital is governed by [2006] Spin quantum number Magnetic quantum number Principal quantum number Azimuthal quantum number 40. [2007], (ii), (iii) and (iv) (ii), (iv) and and (iii) (ii), (iii) and (iv) 41. If uncertainty in position and momentum are equal, then uncertainty in velocity is: [2008] 42. The measurement of the electron position if associated with an uncertainty in momentum, which is equal to 1 10 18 g cm s 1. The uncertainty in electron velocity is, (mass of an electron is 9 10 28 g) [2008] 1 10 9 cm s 1 1 10 6 cm s 1 1 10 5 cm s 1 1 10 11 cm s 1 43. The energy absorbed by each molecule (A2) of a substance is 4.4 10 19 Jand bond energy per molecule is 4.0 10 19 J. The kinetic energy of the molecule per atom will be: [2009] 2.2 10 19 J
16 2.0 10 19 J 4.0 10 20 J 2.0 10 20 J 44. Maximum number of electrons in a subshell of an atom is determined by the following: [2009] 2 l + 1 4 l 2 2 n 2 4 l + 2 45. Which of the following is not permissible arrangement of electrons in an atom? [2009] n = 5, l = 3, m = 0, s = + 2 / 1 n = 3, l = 2, m = 3, s = 2 / 1 n = 3, l = 2, m = 2, s = 2 / 1 n = 4, l = 0, m = 0, s = 2 / 1 46. According to MOtheory which of the following lists ranks the nitrogen species in terms of increasing bond order? [2010] 47. Which one of the following species does not exist under normal conditions? [2010] Be2 + Be2 B2 Li2 48. A 066. kg ball is moving with a speed of 100 m/s. The associated wavelength will be ( h=6.6 10-34 Js) [2011] 1.0 u 10 32m 6.6 u 10 32m 6.6 u 10 34m 1.0 u 10 35m 49. The total number of atomic orbitals in fourth energy level of an atom is: [2011] 8 16 32 4 50. Which of the following has the minimum bond length? [2011] O2 + O2 O2 2 O2 51. [2011] 52. If n = 6, the correct sequence for filling of electrons will be:[2011] 53. According to the Bohr Theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon? [2011 M] [2011] n = 6 to n = 1 n = 5 to n = 4 n = 6 to n = 5 n = 5 to n = 3 54. The pairs of species of oxygen and their magnetic behaviours are noted below. Which of the following presents the correct description? [2012]
17 55. Maximum number of electrons in a subshell with: l = 3 and n = 4 is: [2012] 14 16 10 12 56. The correct set of four quantum numbers for the valence electron of rubidium atom (Z= ) 37 is [2012] 5, 1, + 2 / 1 6, 0, 2 /1 + 0 5, 0, 2 /1 + 0 5, 1, 2 /1 + 0 57. The orbital angular momentum of a p- electron is given as: [2013] n = 3, l = 1 and m = 1 [2013] 6 4 2 10 60. [2013] Larger the value of n, the larger is the orbit radius. Equation can be used to calculate the change in energy when the electron changes orbit. For n = 1, the electron has a more negative energy than it does for n = 6 which mean that the electron is more loosely bound in the smallest allowed orbit. The negative sign in equation simply means that the energy or electron bound to the nucleus is lower than it would be if the electrons were at the infinite distance from the nucleus. 61. 58. The value of Planck s constant is 6.63 10 34 Js. The speed of light is 3 10 17 nm s. 1 Which value is closest to the wavelength in nanometer of a quantum of light with frequency of 6 10 15 s 1? [2013] 25 50 75 10 59. What is the maximum numbers of electrons that can be associated with the following set of quantum numbers? [2013] SOLTIONS 1. 2.
18 3. 4. 14. 5. 6. 7. 15. 8. 16. 17. 9. 10. 11. 18. 19. 20. 12. 13. 21.
19 22. 27. 28. 29. 23. 24. 25. 30. 31. 26.
20 32. 34. 40. 35. 41. 36. 37. 42. 38. 43. 44. 39. 45.
21 46. 47. 57. 48. 49. 50. 58. 51. 59. 52. 53. 54. 60. Energy of an electron at infinite distance from the nucleus is zero. As an electron approaches the nucleus, the electronattraction increases and hence the energy of electron decreases and thus becomes negative. Thus as the value of n decreases, i.e. lower the orbit is, more negative is the energy of the electron in it. 61. 55. 56.