33 Years NEET-AIPMT Chapterwise Solutions - Physics 2020

Nuclei
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121
89. The binding energy of deuteron is 2.2 MeV and that
of 2
4 He is 28 MeV. If two deuterons are fused to
form one 2
4 He then the energy released is
(a) 30.2 MeV (b) 25.8 MeV
(c) 23.6 MeV (d) 19.2 MeV (2006)
90. In any fission process the ratio
mass of fission products
mass of parent nucleus is
(a) equal to 1
(b) greater than 1
(c) less than 1
(d) depends on the mass of the parent nucleus.
(2005)
91. If in a nuclear fusion process the masses of the fusing
nuclei be m 1 and m 2 and the mass of the resultant
nucleus be m 3 , then
(a) m 3 = m 1 + m 2 (b) m 3 = |m 1 – m 2 |
(c) m 3 < (m 1 + m 2 ) (d) m 3 > (m 1 + m 2 )
(2004)
92. Solar energy is mainly caused due to
(a) burning of hydrogen in the oxygen
(b) fission of uranium present in the Sun
(c) fusion of protons during synthesis of heavier
elements
(d) gravitational contraction (2003)
93. Nuclear fission is best explained by
(a) liquid droplet theory
(b) Yukawa p-meson theory
(c) independent particle model of the nucleus
(d) proton-proton cycle. (2000)
94. Which of the following is used as a moderator in
nuclear reaction?
(a) Cadmium (b) Plutonium
(c) Uranium (d) Heavy water (1997)
95. Energy released in the fission of a single
235
92U
235
nucleus is 200 MeV. The fission rate of 92 U filled
reactor operating at a power level of 5 W is
(a) 1.56 × 10 –10 s –1 (b) 1.56 × 10 11 s –1
(c) 1.56 × 10 –16 s –1 (d) 1.56 × 10 –17 s –1 (1993)
96. Solar energy is due to
(a) fusion reaction (b) fission reaction
(c) combustion reaction (d) chemical reaction
(1992)
ANSWER KEY
1. (a) 2. (b) 3. (c) 4. (c) 5. (a) 6. (a) 7. (a) 8. (c) 9. (b) 10. (d)
11. (a) 12. (d) 13. (d) 14. (b) 15. (c) 16. (a) 17. (c) 18. (b) 19. (c) 20. (b)
21. (c) 22. (a) 23. (d) 24. (c) 25. (a) 26. (a) 27. (a) 28. (b) 29. (c) 30. (a)
31. (c) 32. (c) 33. (b) 34. (d) 35. (a) 36. (*) 37. (d) 38. (c) 39. (d) 40. (c)
41. (d) 42. (b) 43. (d) 44. (b) 45. (b) 46. (b) 47. (c) 48. (c) 49. (d) 50. (c)
51. (d) 52. (c) 53. (a) 54. (c) 55. (a) 56. (b) 57. (c) 58. (d) 59. (a) 60. (a)
61. (c) 62. (d) 63. (a) 64. (a) 65. (b) 66. (c) 67. (a) 68. (d) 69. (b,d) 70. (c)
71. (a) 72. (b) 73. (b) 74. (b) 75. (a) 76. (a) 77. (d) 78. (b) 79. (d) 80. (a)
81. (c) 82. (d) 83. (d) 84. (a) 85. (a) 86. (c) 87. (c) 88. (a) 89. (c) 90. (c)
91. (c) 92. (c) 93. (a) 94. (d) 95. (b) 96. (a)
Hints & Explanations
1. (a) : Isotones means number of neutron remains
same.
2. (b) : Z is number of protons and A is the total
number of protons and neutrons.
3. (c) : Mass number = atomic number + no.
of neutrons
For hydrogen, number of neutrons = 0
So, mass number = Atomic number.
Hence mass number is sometimes equal to atomic
number.
4. (c) : Let 5 B 10 be present as x% so percentage of 5 B 11
= (100 – x)
\ Average atomic weight
10x+ 11( 100 −x)
=
= 10. 81 ⇒ x = 19
100
\ % of 5 B 11 is 100 – 19 = 81. Ratio is 19 : 81.
5. (a) : Nucleus contains only neutrons and protons.
6. (a) : Z = 11 i.e., number of protons = 11,
A = 23
\ Number of neutrons = A – Z = 12
Number of electron = 0 (No electron in nucleus)
Therefore 11, 12, 0 is the correct answer.
7. (a) : As 6 C 13 and 7 N 14 have same number of neutrons
(13 – 6 = 7 for C and 14 – 7 = 7 for N), they are isotones.