Atoms Mock Test – Class 12 Physics

1. For a fixed target nucleus, an -particle passing closer to the nucleus suffers a larger deflection mainly because

2. A table compares statements about a revolving electron in Rutherford’s atom.

The row that conflicts with the classical stability argument is

3. In Bohr’s model, radiation is emitted when the electron

4. Study the spectrum-type table.

The row that needs correction is

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

6. A model keeps Rutherford’s central nucleus but wants to avoid classical collapse of the electron. The needed new idea is that

7. For a fixed value of , increasing in the Rydberg formula makes the spectral lines of that series approach

8. A hydrogen atom in can emit photons by transitions among lower levels. The number of distinct spectral lines possible as it finally reaches is

9. A record of radiation from three sources is shown below.

The correct identification is

10. In a hydrogen-like ion, the wavelength of a fixed transition is one-ninth of the corresponding hydrogen wavelength. The value of for the ion is

11. Consider the following statements.
I. connects photon energy with frequency.
II. connects photon energy with wavelength.
III. For photons, higher frequency means longer wavelength in vacuum.

12. As increases for hydrogen, the total energy

13. For the first line of a hydrogen series with fixed , the value of is

14. The Lyman series lies in the ultraviolet region mainly because its transitions end at , giving

15. The expression gives energy in joule when , , and are used in SI units. The SI unit of may be written as

16. In hydrogen, a sample is excited up to . Only the spectral lines ending at are observed. The number of possible Balmer lines from this sample is

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

18. The stability of Bohr’s atom depends most directly on the idea that

19. A hydrogen atom is excited to . The maximum number of distinct emission lines possible as atoms in a sample return to lower levels is

20. A comparison of central atomic-model ideas is shown below.

The row that needs correction is

21. The link between atomic structure and electrostatics appears because

22. An electron in a one-electron ion has orbit radius and total energy . The values of and are

23. A symbolic derivation uses two relations:
I.
II.
Together, these relations show that allowed radii are not arbitrary because

24. Assertion: Thomson’s model was able to explain the electrical neutrality of atoms.
Reason: In Thomson’s model, electrons were embedded in a sphere of positive charge.

25. A single hydrogen atom at falls directly to . The emitted photon belongs to the

26. Thomson’s atomic model pictured the atom as

27. A model that explains alpha scattering but not atomic stability or spectra is most likely

28. A line in the hydrogen spectrum is described by and . The Rydberg expression for this line is

29. The visible lines of the hydrogen spectrum were first systematically described in the Balmer region. These lines are important because they show

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

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

32. The statement “impact parameter is the distance between the nucleus and the final scattered path” is inaccurate because is measured from

33. A graph is drawn between electron speed and for a fixed hydrogen-like ion. The graph is a straight line through the origin. The slope is proportional to

34. The approximate value of the Bohr radius is

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

36. Compare the series limits of Lyman, Balmer, and Paschen series. The largest limiting wavenumber belongs to

37. A limitation of Bohr’s model related to probability is that it does not describe the electron as

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

39. A statement says, “The nucleus has nearly all the mass, so it must occupy nearly all the volume of the atom.” The best response is that

40. In Rutherford’s model, if an electron radiates energy continuously, its orbit should

41. For , a one-electron ion makes a transition from to . Using the hydrogen energy , the emitted photon energy and wavelength are closest to

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

43. For hydrogen, and . A photon of energy is incident on an atom in . The best conclusion is that

44. Study the following size-comparison table.

The row that gives an incorrect comparison is

45. A claim says, “The zinc sulphide screen was used to scatter alpha particles strongly.” The better correction is that the screen was used to

46. Consider the following statements about limitations of Rutherford’s model.
I. It could not explain why atoms are stable against electron collapse.
II. It could not explain the discrete line spectra of atoms.
III. It explained the exact wavelengths of hydrogen spectral lines.

47. For absorption in Bohr’s model, the electron moves upward from energy to energy , where . The absorbed photon must satisfy

48. A neutral atom in Thomson’s model was neutral because

49. A hydrogen spectral line is produced by the transition . This line belongs to the

50. A photon’s wavelength is reduced from to . Its frequency and energy change as