Atoms Mock Test – Class 12 Physics

1. A data sheet lists the following conversion: . The energy in joules is

2. A hydrogen atom is excited to . The maximum number of distinct emission lines that end specifically in is

3. A passage describes two alpha-particle paths near the same nucleus.

Ignoring other complications, the ratio of repulsive force in Case 2 to that in Case 1 at those stated distances is

4. Consider the following statements about Rutherford’s scattering observations.
I. Most -particles passed through the foil without appreciable deflection.
II. A few -particles were scattered through large angles.
III. All -particles bounced back from the foil.

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

6. In a head-on scattering calculation, the target nucleus changes from charge to , while the alpha-particle kinetic energy remains the same. The closest approach distance changes from to

7. A proposed orbit contains complete de Broglie wavelengths around its circumference. In the Bohr-de Broglie interpretation, the corresponding value of is

8. Study the following size-comparison table.

The row that gives an incorrect comparison is

9. A neutral helium atom has two electrons. The main reason Bohr’s simple one-electron formula cannot be applied directly to it is that

10. The most complete statement about Bohr’s model is that it

11. A hydrogen atom initially in absorbs a photon of wavelength . Using , the atom can be excited to

12. For the series limit of a hydrogen series with fixed , the value of is taken as

13. A hydrogen atom emits a photon when its electron moves from to . Using and , the photon energy is closest to

14. The radius of the orbit of hydrogen is

15. A student compares kinetic energy and potential energy in atomic models. Kinetic energy is most directly associated with

16. For a fixed target and fixed scattering angle in Rutherford scattering, increasing the kinetic energy of the incident -particles reduces large-angle scattering mainly because

17. A hydrogen atom in the ground state receives of energy. The electron can be

18. A table gives possible descriptions of electron motion in Bohr’s model.

The row that conflicts with Bohr’s model is

19. In a comparison of atomic spectra, a line spectrum differs from a continuous spectrum because a line spectrum has

20. A claim states, “Large deflection occurs because the nucleus attracts the -particle strongly.” The claim should be rejected because

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

22. A table compares model features with spectral explanation.

The row that gives an unsuitable spectral statement is

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

24. If an electron in Rutherford’s atom were allowed to radiate energy continuously while revolving, the emitted radiation would be expected to have

25. Assertion: Bohr’s model kept the central nucleus of Rutherford’s model.
Reason: Bohr’s model was built by adding quantum postulates to the nuclear atom.

26. The empirical Rydberg formula for hydrogen is used mainly to calculate

27. A graph description is given below.

This spacing pattern means that transitions between very high neighbouring levels have

28. A student writes the Rydberg formula for hydrogen as with . The main problem is that this gives

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

30. Combining Bohr’s angular momentum rule with the circular force-balance condition is mainly used to derive

31. A graph of hydrogen energy levels shows the levels getting closer together as increases. The correct reason is that

32. The total energy of a bound electron in the Bohr orbit of a hydrogen-like atom is

33. A graph of hydrogen energy levels is drawn with at the top and negative levels below it. A transition arrow points upward from to . This arrow represents

34. A claim says, “An electron in a circular orbit has constant speed, so it has no acceleration and should not radiate.” The flaw is that

35. Use the situation below.

The best interpretation is that the cool gas

36. A hydrogen line has and . Its wavenumber is

37. Let denote the electron speed in the first Bohr orbit of hydrogen. For , the electron speed in the first orbit is

38. The energy of the level of hydrogen is

39. A table lists four claims about bound Bohr states.

The row that needs correction is

40. For a head-on -particle approach, increasing the initial kinetic energy while keeping the target nucleus unchanged makes the closest approach distance

41. The ionisation energy of from its ground state is

42. The main reason Bohr’s model was not just a repetition of Rutherford’s model is that Bohr added

43. 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

44. A graph description is given below.

As increases, the plotted points

45. The idea of de Broglie wavelength enters atomic structure because an electron can show

46. The observed stability of ordinary atoms means that

47. A table lists changes in head-on scattering conditions.

The row that gives the wrong effect on is

48. For the Balmer series limit, the wavenumber is . Taking , the limiting wavelength is closest to

49. An atom absorbs a photon of energy and moves from an initial level . The final energy level is

50. Assertion: Rutherford’s model could not explain the observed stability of atoms.
Reason: According to classical theory, an accelerated charged electron should radiate energy while revolving.