Nuclei Mock Test – Class 12 Physics

1. The masses of a proton, a neutron, and an electron are compared. The best qualitative order is:

2. In a nuclear reaction, the -value is most directly the:

3. A radioactive decay is written as . The particle must be:

4. A nucleus has the same mass number as but one less proton. Its notation is best represented by:

5. The nuclear equation represents:

6. Half-life is the time in which:

7. The pair and should be classified as:

8. A nucleus P has and . A nucleus Q has and . Based on , the better-bound nucleus is:

9. The saturation of nuclear force helps explain why the binding energy per nucleon for many medium and heavy nuclei is:

10. The main difference between a controlled reactor chain reaction and an uncontrolled chain reaction is:

11. A radioactive sample contains two independent isotopes P and Q. At , their activities are and , respectively. The half-lives are for P and for Q. The total activity after is:

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

13. A heavy nucleus has and . Its neutron-proton ratio is closest to:

14. In a controlled nuclear reactor, the purpose of control rods is to:

15. Assertion: Alpha particles have low penetrating power but high ionising power.
Reason: Alpha particles are relatively massive and carry charge .

16. A final comparison of nuclear processes is given below.

Which statement about the table is most suitable?

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

18. The symbol in the notation is decided by:

19. Match each classification with its defining condition.

20. A nuclear reaction is studied with the reactants initially at rest. The total rest mass of the reactants is , and the total rest mass of the products is also . No external energy is supplied, but the products are claimed to have extra kinetic energy. Which conclusion is most appropriate?

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

22. Two deuterium nuclei combine to form a heavier light nucleus. The initial total nucleon number is . If the average binding energy per nucleon increases by , the approximate energy released is:

23. A nucleus with mass number undergoes alpha decays and some beta decays. Since beta decays do not change , the ratio of final nuclear radius to initial nuclear radius is closest to:

24. A sample has activity . If , its activity is:

25. In a thermal reactor, a moderator slows neutrons mainly through collisions. A good moderator should:

26. The relation between mass defect and binding energy is sometimes misunderstood as “mass defect is a loss of matter from the nucleus.” A better interpretation is:

27. Study the table and identify the row that correctly connects a region of the curve with the energy-releasing process.

28. Assertion: The chemical symbol in is fixed by , not by .
Reason: The atomic number gives the number of protons, and proton number determines the element.

29. Electron capture changes a nucleus in a way similar to beta plus decay because it:

30. A fusion reaction has reactant mass and product mass . The -value is closest to:

31. Consider the following statements about radioactive emissions.
I. Alpha particles have relatively high ionising power.
II. Gamma rays have high penetrating power.
III. Beta minus particles are helium nuclei.
Which statements are valid?

32. A fission equation is proposed:

The value of required by mass-number conservation is:

33. A distance of is equal to:

34. A proposed beta plus decay has neutral atomic mass difference . Taking , the decay is:

35. A radioactive isotope has molar mass . A sample of mass is pure isotope and has half-life . Taking and , its initial activity is closest to:

36. Consider the decay chain:

The first and second steps are respectively:

37. A atom has . Take , , and . Its binding energy is closest to:

38. The unit of activity, becquerel, is equivalent to:

39. A sample has undecayed nuclei and decay constant . Its activity is:

40. A nucleus with and has equal to:

41. 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?

42. The nuclear radius relation implies that nuclear volume is proportional to:

43. Nuclear fission is best described as:

44. A reaction releases per event. The energy per event in , using , is:

45. In age estimation, a sample's present activity is of the activity of a fresh sample of the same amount of material. If the half-life is , the estimated age is:

46. The equation obeys charge conservation because:

47. Assertion: A mass defect written in can be converted to energy in by multiplying by .
Reason: is approximately .

48. A mass table lists a neutral atomic mass and a nuclear mass for the same nuclide. The nuclear mass is smaller mainly because it does not include:

49. Two nuclei have mass numbers and . If the same value of is used for both, the best comparison is:

50. A row of a nuclear-decay table is shown below.

Which row is correct?