CBSE Guess > Papers > Important Questions > Class IX > 2009 > Science > Science By : Mr M. p. Keshri
CBSE CLASS I X
Structure Of The Atoms (Solved)
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Q. 36. State the model of an atom proposed by J. J. Thomson.
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Q. 37. Give an evidence in support of the existence of nucleus in an atom.
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Q. 38. Who discovered neutrons and how ?
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Q. 39. What is nucleus ?
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Q. 40.How we determine the number of positive charges on the nucleus ?
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Q. 41. “In Rutherford’s experiment, some of the α-particles were bombarded on a gold foil, were repelled”. Give reason.
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Q, 42. Charged particles are present in the atom, then why is it neutral ?
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Q. 43. Give evidence to show that an atom has a lot of empty space within it.
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Q. 44. How was it established that atomic nuclei are positively charged ?
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Q. 45. Why Rutherford believed that central part of the atom is positively charged ?
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Q. 46. What is the magnitude of the size of an atom in comparison to its nuclear size ?
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Q. 47. State the characteristic features of the Thomson model of atom.
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Q. 48. Describe the essential properties of nucleus of an atom. Compare these properties with the properties of an electron.
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Q. 49. State the basis on which Rutherford rejected the model of atom as proposed by J. J. Thomson.
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Q. 50. State the model of atom proposed by Rutherford.
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Q. 51. State the main objection to Rutherford’s model of atom.
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Q. 52. Describe the nuclear ( Bohr’s ) model of an atom.
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Q. 53. Can we use foil of any other metal instead of gold in Rutherford experiment of scattering of alpha particles ?
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Q. 54. Why does the energy of the atom increases when an electron jumps from energy level K to energy level L ?
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Q. 55. Why are the orbits or shells in which the electrons revolve around the nucleus of an atom called energy levels ?
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Q. 56. How does Bohr’s model of atom explain characteristic spectra of different atoms and ionization of gases in the discharge tube experiment ?
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Q. 57. What is an orbit ?
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Q. 58. State the essential features of the model of atom proposed by E. Rutherford. How is it different from that proposed by J. J. Thomson ?
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Q. 59. State the fundamental contributions of E. Rutherford in understanding the structure of atom.
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Q. 60. State the concept incorporated by Neils Bohr in the model of atom proposed by him.
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Q. 61. What is neutron ? State its Characteristics.
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Q. 62.Compare an electron, a proton and a neutron in respect of their symbol, mass and charge.
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Q. 63. What are the fundamental particles present in an atom of any element ?
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Q. 64. What are similarities and dissimilarities between protons and neutrons ?
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Q. 65. What is effect of addition of a neutron to the nucleus of an atom ?
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Q. 66. What constituent properties of the atom determine the following :
(i) Mass of the atom
(ii) Size of the atom
(iii) Charge on the nucleus.
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Q. 67. Why scattering experiment cannot be used to prove the existence of neutrons ?
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Q. 68. “Nucleus does not contain any electron. Even then the β-particles emission has been described as the ejection of an electron from the nucleus.” Comment.
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Q. 69. What is the effect of emission of γ-rays on the nucleus ?
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Q. 70. Why is extra nuclear part neglected when calculating the mass of the atom ?
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Q. 71. State the importance of extra nuclear part of the atom when its mass is negligible.
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Q. 72. On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole ?
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Q. 73. On the basis of Rutherford’s model of an atom, which sub-atomic particle is present in the nucleus of an atom ?
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Q. 74. Draw a sketch of Bohr’s model of an atom with three shells.
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Q. 75. What do you think would be the observation if the a-particle scattering experiment is carried out using a foil of metal other than gold ?
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Q. 76. Name the three sub-atomic particles of an atom.
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Q. 77. Helium atom has an atomic number of 4u and has two protons in the nucleus. How many neutrons does it have ?
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