Atoms Mock Test – Class 12 Physics

1. A line has wavenumber . If it belongs to the hydrogen series with , the value of is

2. For a fixed hydrogen-like ion, the graph of versus is expected to be

3. Study the qualitative scattering table.

The row that conflicts with Rutherford-scattering trends is

4. Compare the hydrogen-like species in the table.

For the emitted photon energies, the correct order is

5. A spectral line splits when an external electric field is applied to the source. The limitation of Bohr’s model highlighted by this observation is its inability to fully explain

6. In Bohr’s circular orbit, the centripetal force needed by the electron is supplied by

7. Thomson’s model could not explain sharp atomic spectral lines because the model had no clear idea of

8. In the de Broglie interpretation of Bohr orbits, an allowed circular orbit is one in which

9. For alpha particles scattered at a fixed large angle, increasing the kinetic energy of the incident alpha beam generally reduces the number scattered into that angle because

10. The gold foil in Rutherford’s experiment had to be very thin so that

11. If a hydrogen atom is excited up to , the maximum number of distinct emission lines possible during all downward transitions is

12. In Bohr’s model, a stationary orbit is an orbit in which the electron

13. In a Rutherford-scattering record, the number of -particles detected at a fixed large angle is compared for two thin foils of similar thickness. If the target nuclear charge changes from to and the incident -particle energy is unchanged, the large-angle count is expected to

14. In a head-on approach of an -particle toward a positive nucleus, the deflection is maximum because

15. For the Lyman series limit of hydrogen, the Rydberg formula uses

16. If an atom is mostly empty space, then the volume occupied by the nucleus must be extremely small compared with the atomic volume. This idea is consistent with

17. Bohr’s angular momentum postulate states that the electron can revolve only in orbits for which its angular momentum is

18. In a simple excitation experiment, hydrogen atoms in the ground state are supplied with of energy. The most direct interpretation is

19. A hydrogen line has wavenumber . The transition is represented by

20. A claim says, “Most -particles passed straight through, so the atom has no positive charge.” The better interpretation is that

21. For two hydrogen-like species, the orbit with and the orbit with have radii

22. An -particle approaching a gold nucleus is deflected because

23. The same element produces a characteristic set of spectral lines because

24. Use the comparison below.

The correct identification of P, Q, and R is

25. An energy-level diagram shows three downward arrows in hydrogen:

The emitted photon with the greatest energy is from

26. Consider the following statements about Rutherford’s nuclear model.
I. The atom contains a small positively charged nucleus.
II. Electrons revolve around the nucleus.
III. The atom is neutral when the number of electrons equals the nuclear charge number .

27. Use the graph description below.

The slope of this graph represents

28. A passage describes an electron in a Bohr atom.

According to Bohr’s postulate, during this time the electron

29. The ground-state energy of hydrogen is

30. The impact parameter in alpha-particle scattering is the

31. In the Bohr model of a hydrogen-like atom, the speed of the electron in the orbit is proportional to

32. An atomic model that includes charged particles, circular motion, and radiation must be able to deal with all of the following ideas except

33. A graph of hydrogen energy levels shows a downward arrow from to and another from to . Compared with the photon, the photon has

34. Read the record below and identify the line that would cause a unit error in a photon-energy calculation.

35. Match the hydrogen spectral series with its fixed final level.

36. In the de Broglie explanation of Bohr orbits, increasing the electron speed while keeping its mass fixed makes its wavelength

37. A head-on alpha-particle approach toward a nucleus corresponds to

38. A table lists three Bohr-model quantities for hydrogen-like atoms.

The row that needs correction is

39. The usual order of atomic radius is about , while the usual order of nuclear radius is about . This comparison shows that

40. A photon has wavelength . Take , , and . Its energy is closest to

41. A table lists possible angular momenta for an electron in Bohr’s atom.

The row that needs correction is

42. The photon energy involved in an atomic transition is connected with frequency by

43. In the usual notation for an atom, mainly represents

44. Use the energy-level description below.

The transition that emits the longest-wavelength photon is

45. The experimental chamber was evacuated in Rutherford’s scattering experiment mainly to

46. A graph description is given below.

The arrow represents

47. A head-on alpha-scattering case has initial kinetic energy . The target nucleus has charge . The alpha particle has charge . The electrostatic potential energy at closest approach is

48. An alpha particle of kinetic energy approaches a gold nucleus head-on. Take , , , and . The closest approach is approximately

49. A claim says, “Bohr’s model is useful only because it explains alpha-particle backscattering.” The better statement is that Bohr’s model mainly explains

50. In hydrogen, two downward transitions are compared: transition P is , and transition Q is . The photon from transition Q has