Atoms

1.1 According to classical theory, Rutherford atom was (1) Electrostatically stable (2) Electrodynamically unstable. (3) Semi stable
(4)Stable

1.2. The angular momentum of an electron in a hydrogen atom is proportional to (where r is radius of orbit)

1.4. Thickness of the foil of gold used in α- particle scattering experiment is (1) 2.1 × 10–⁷ m (2) 3.5 × 10–⁵ (3)2.1 × 10–⁹ m (4)3.5×10–⁶ m

1.5. The scattering α-particles were observed through a rotatable detector consisting of a screen of (1) Copper sulphide (2) Zinc sulphide (3) Graphite . (4) Gold]

1.6. In Rutherford’s experiment, scattering of more than 1° was observed in (1) 14% of the incident α-particles (2) About 0.14% of the incident α- particles (3) About 1.4% of the incident α-particles. (4) About 0.014% of the incident α-particles ]

1.7. In scattering experiment, α-particles were deflected by (1) Repulsive force of electrons (2) Repulsive force of gold nucleus. (3) Attractive force of electrons. (4) Attractive force of gold nucleus ]

[❓ 1.8. Energy of the beam of α-particles used by Geiger and Marsden in scattering experiment is (1) 2.2 MeV (2) 4.2 MeV (3) 5.1 MeV .(4) 5.5 MeV]

[❓ 1.9. Source of α-particles used in scattering experiment was (1) ₈₂ Bi ²⁴⁶ (2) ₈₁Bi²⁴⁶ (3) ₈₁Bi²¹⁴ (4) ²¹⁴ ₈₃ Bi]

[❓ 10. In scattering experiment, find the distance of closest approach, if a 6 MeV α-particle is used (1) 3.2 × 10–¹⁶ m (2) 2 × 10–¹⁴m (3) 4.6 × 10–¹⁵m (4) 3.2 × 10–¹5 m]

1.11. When a hydrogen atom is raised from the
ground state to third state (1) Both kinetic energy and potential energy increase (2) Both kinetic energy and potential energy decrease (3) Potential energy increases and kinetic
energy decreases (4) Potential energy decreases and kinetic
energy increases

[❓ 1.12. What is the angular momentum of an electron in Bohr’s hydrogen atom whose energy is –3.4 eV ? ]

[❓ 1.13. The energy levels of a certain atom for first, second and third levels are E, 4(E/3) and 2E respectively. A photon of wavelength λ is emitted for a transition 3 → 1. What will be the wavelength of emission for transition 2 → 1 ?]

[❓ 1.14. The ground state energy of H – atom is –13.6 eV. The energy needed to ionize H – atom from its second excited state is (1) 1.51 eV (2) 3.4 eV (3) 13.6 eV (4) 12.1 eV ]

[❓ 1.14. The ground state energy of H – atom is –13.6 eV. The energy needed to ionize H – atom from its second excited state is (1) 1.51 eV (2) 3.4 eV (3) 13.6 eV (4) 12.1 eV ]

[❓ 15. The angular speed of electron in the nth orbit of hydrogen atom is (1) Directly proportional to n² (2) Directly proportional to n. . (3)Inversely proportional to n³. (4)Inversely proportional to n ]

[❓ 2.1. As the n (number of orbit) increases, the difference of energy between the consecutive energy levels (1) Remains the same (2)Increases (3) Decreases (4)Sometimes increases and sometimes decreases ]

[❓ 2. 2 The ratio of minimum to maximum wavelength of radiation emitted by transition of an electron to ground state of Bohr’s hydrogen atom is ]

[❓ 2 .3. Which of the following transition in a hydrogen atom emit photons of lowest frequency? (1) n = 2 to n = 1 (2) n = 4 to n = 2 (3) n = 4 to n = 3 (4) n = 3 to n = 1 ]

[❓ 2.4. If the electron in hydrogen atom jumps from third orbit to second orbit, the wavelength of the emitted radiation is given by ]

[❓ 2.5. When an electron is excited to nth energy state in hydrogen, the possible number of spectral lines emitted are ]

[❓ 2.6. Which series of hydrogen atom lie in infrared region? (1) Lyman (2) Balmer (3) Brackett, Paschen and Pfund (4) All of these ]

[❓ 2.7. The wavelength of first member of Balmer series in hydrogen spectrum is λ. Calculate the wavelength of first member of Lyman series in the same spectrum (1) (5/27) λ (2) (4/27)λ (3) (27/5)λ. (4) (27/4)λ]

Answer -

❓ 2.9. An X-ray tube has a short wavelength end at 0.45Å. The voltage of tube is (1) 450000 V (2) 9600 V (3) 27500 V. (4)60600 V ]

[❓ 2.10. The wavelength of the Kα line for an element of atomic number is λ. The wavelength of the Kα line for an element of atomic number 29 is ]

[❓ 2.10. The wavelength of the Kα line for an element of atomic number is λ. The wavelength of the Kα line for an element of atomic number 29 is ]

[❓ 2.11. The magnetic field induction produced at the centre of orbit due to an electron revolving in nth orbit of hydrogen atom is proportional to (1) n–³ (2) n–⁵ (3) n⁵ (4) n³]

[❓ 2.12. If the radius of the first orbit of hydrogen atom is 5.29 × 10–¹¹ m, the radius of the second orbit will be (1) 21.16 × 10–¹¹ metre (2) 15.87 × 10–¹¹metre (3) 10.58 × 10–¹¹metre (4) 2.64 × 10–¹¹ metre ]

[❓ 2.13. In Bohr’s model of the hydrogen atom, the ratio between the period of revolution of an electron in the orbit of n = 1 to the period of revolution of the electron in the orbit n = 2 is (1) 1 : 2 (2) 2 : 1. (3) 1 : 4 (4) 1 : 8 ]

[❓ 14. The ratio of the energies of the hydrogen atom in its first excited state to second excited state is (1) 1/4 (2) 4/9. (3) 9/4 (4) 4]