CBSE Physics Atom, Molecule, Nuclei Expected Questions : Unit X
[Short/Very Short Answer Questions-1, 2 Marks]
1. Name the series of hydrogen spectrum lying in ultraviolet region.
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2. The total energy of an electron in the first excited state of the hydrogen atom is about —3.4eV. What is the P.E. of the electron in this state ?
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3. What is Bohr’s quantisation condition for angular momentum of an electron in the second orbit ?
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4. What is a-particle ? In the reaction zXA = a + Y, give the atomic number and mass number ofY.
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5. What is beta decay ? Give one example of this decay.
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6. Does the ratio of neutrons to protons in a nucleus increase, decrease or remain the same after the emission of an a-particle ?
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7. Write the number of protons and neutron in 56Ba
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8. Write the number of photons and neutrons in B.
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9. Why is the energy distribution of beta rays continuous ?
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10. What is the angular momentum of an electron in the 3rd Bohr orbit of an atom ?
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11. Write down the equation of decay of a free neutron.
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12. State Bohr’s postulates for explaining the spectrum of hydrogen atom.
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13. Write the relation connecting the radius R of nucleus and its mass number A.
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14. What is the difference between isotopes and isobars ?
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15. Define radius of nucleus.
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16. What is nuclear night ?
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17. What is nuclear holocaust ?
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18. Name two radioactive elements which are not found in observable quantity in nature.
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19. What is the ratio of radii of nuclei of mass A1 and A2 ?
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