Atoms Mock Test – Class 12 Physics

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

The row that needs correction is

2. In a one-electron ion, an electron in has the same speed as an electron in hydrogen at . The ion’s is

3. A simple description says that an atom contains a small central nucleus and electrons around it. In this description, the nucleus contains

4. A hydrogen atom absorbs a photon of energy while initially in the ground state. The final level is closest to

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

6. A thick foil would be unsuitable for a clean Rutherford-type scattering experiment because it would

7. The Rydberg constant appears in the hydrogen spectrum formula. Its usual SI unit is

8. In an emission spectrum of an atom, bright lines are produced when

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

10. A hydrogen atom emits a photon during the transition . This photon belongs to the same spectral series as the photon from

11. A hydrogen atom in is just ionised by a photon whose threshold wavelength is closest to , using . The energy threshold used in this calculation is

12. The phrase “stationary state” in Bohr’s model refers most closely to

13. Study the table of spectral processes.

The row that needs correction is

14. The observation that most -particles passed through the foil almost undeflected becomes more understandable when we remember that

15. In the symbol language used for atoms, the pair and is most useful because it tells us

16. During the transition , a one-electron ion emits a photon of wavelength . If the corresponding hydrogen transition has wavelength , the value of is closest to

17. In atomic calculations, the energy unit is commonly used because atomic energy changes are

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

19. Match the Rydberg-formula element with its meaning.

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

21. A microscope was used with the zinc sulphide screen because

22. 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

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

For the emitted photon energies, the correct order is

24. Starting from the Bohr relations and , the reason finally varies as is that

25. The second Bohr level of a one-electron ion has energy . The value of is

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

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

28. For , . The radius of its first Bohr orbit is

29. In the hydrogen Rydberg formula, the condition on the integers is

30. Match the symbols in Bohr’s angular momentum postulate with their meanings.

31. Consider the following statements about impact parameter and scattering.
I. Large usually gives a small scattering angle.
II. Small usually gives a large scattering angle.
III. The head-on case has .

32. The statement “the nucleus is tiny compared with the atom” is most directly a statement about

33. The hydrogen line has wavelength approximately . For the corresponding transition in , the wavelength is approximately

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

35. If an electron matter wave around an orbit satisfies , then using gives

36. A first sketch of atomic structure shows a compact positive centre and electrons in the surrounding region. The compact positive centre is called the

37. In Rutherford’s nuclear model, electrons are placed

38. An atom has two energy levels separated by . A photon is emitted when the atom moves from the higher level to the lower level. The photon frequency is

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

40. In Bohr’s model, the statement means that

41. Study the table of hydrogen transitions.

The row that needs correction is

42. The ionisation energy of from its ground state is

43. 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

44. Hydrogen gas gives a line spectrum rather than a continuous spectrum. This means that hydrogen atoms

45. Study the qualitative scattering table.

The row that conflicts with Rutherford-scattering trends is

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

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

The row that gives the wrong effect on is

48. A graph description is given below.

If the graph represents atomic and nuclear sizes, the correct identification is

49. Band spectra are most commonly associated with molecules rather than isolated atoms because molecules have

50. 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