Nuclei Mock Test – Class 12 Physics

1. The atomic mass unit is defined using which reference?

2. A pair of nuclides has the same but different . A learner calls them isotopes because their total nucleon number is the same. The better classification is:

3. In stars, gravity is important for fusion because it:

4. A counter records from a radioactive source at and after . The background count is . The half-life of the source is closest to:

5. A radioactive dating measurement gives present activity times the activity of a fresh sample of the same isotope and same amount. If , the age is closest to :

6. Two nuclei have the same neutron number . One has and the other has . Their mass numbers are respectively:

7. The two nuclides and have the same mass number. Their neutron numbers are:

8. For a neutral atom , the three numbers , , and denote protons, neutrons, and electrons. The row that is valid is:

9. A source emits particles with charge . The radiation is deflected in an electric field toward the positive plate. The most suitable identification is:

10. A neutral atom has and . How many electrons does the neutral atom have?

11. The line between nuclear radiation and atomic-shell radiation is clearest in which comparison?

12. Two nuclides have the same atomic number but different mass numbers. The most suitable name for such nuclides is:

13. Using , , and , the approximate nuclear density is closest to:

14. Using , the nucleon number density inside nuclei may be estimated as . If and , the nucleon number density is closest to:

15. A compact graph description says:

The better conclusion is:

16. A detector is placed near three sources of nuclear radiation. Source P produces heavy charged particles, source Q produces light negatively charged particles, and source R produces neutral photons. The sources are most likely emitting:

17. A fossil has present activity of the activity of a living sample of the same carbon content. If the half-life is , its approximate age is:

18. A proton-rich nucleus lies below the band of stability on an -versus- graph. A likely way for it to move toward stability is:

19. The quantity in the nuclear radius relation has the unit:

20. A data sheet gives , , and for a radioactive sample. The entry with inverse-time unit is:

21. A sample of releases about per fission. If of nuclei completely undergoes fission, the total energy released is closest to :

22. In an alpha decay from a parent initially at rest, the alpha particle usually gets more kinetic energy than the daughter nucleus because:

23. The energy released in fission is large because:

24. If a nucleus with mass number is compared with another nucleus having mass number , the density ratio predicted by the simple radius law is:

25. A radioactive tracer is useful in a system mainly because:

26. A nucleus is imagined in which one proton is far outside the range of nuclear force but still feels electrostatic repulsion from the other protons. What is most likely about its binding to the nucleus?

27. A nucleus with is very heavy. A stability argument says it needs many neutrons. The best reason is:

28. The statement is defined as of the mass of a neutral atom. This definition uses a neutral atom rather than only a carbon nucleus. What does this mainly fix?

29. The penetrating power order for alpha, beta, and gamma radiations is:

30. A reactor is operating steadily. If control rods are inserted further into the core, the immediate intended effect is:

31. A source has activity . The average number of decays in is:

32. A nuclide emits two beta minus particles and one alpha particle in any order. The net change in and is:

33. A neutron-induced fission event releases neutrons. In a certain arrangement, only neutron per fission on average causes another fission. The chain reaction will:

34. The coolant in a nuclear reactor is used to:

35. In an alpha decay, the alpha particle is usually observed with a definite energy rather than a broad continuous range. This is mainly because:

36. Consider the three changes below.

The sequence P, Q, R is:

37. Study the table and identify the row that follows from .

38. A table gives four possible nuclear reactions. Identify the balanced reaction.

39. A nucleus changes from to . If only alpha and beta minus decays are involved, the minimum set of changes is:

40. An isotope has mean life . Its half-life is approximately :

41. The particles called nucleons are listed in the table below. Identify the row that gives the correct pair.

42. The alpha decay equation is mainly based on conservation of:

43. A claim says, “Radioactivity can be stopped by changing only the chemical compound of the radioactive element.” The best evaluation is:

44. A radiation source must be handled with shielding, and the main concern is highly penetrating neutral radiation. The most suitable shield among the following is:

45. Study the table and identify the row that gives the correct relation for radioactive decay.

46. In , the number of protons, neutrons, and electrons is:

47. A proposed reaction has product mass greater than reactant mass. What does this imply about its -value?

48. In beta minus emission, the emitted particle is:

49. The value is called an average quantity because it gives:

50. A sample emits gamma radiation and is used as an external imaging source. The radiation can be detected outside the body mainly because gamma rays: