Nuclear Physics MCQ with Answers

Practice Nuclear Physics MCQ with Answers.

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Nuclear Physics MCQ with Answer


Q1. 238U decays with a half life of 4.51 × 100 years, the decay series eventually ending at 206Pb, which is stable. A rock sample analysis shows that the ratio of the numbers of atoms of 206Pb to 238U is 0.0058. Assuming that all the 206Pb has been produced by the decay of 238U and that all other half-lives in the chain are negligible, the age of the rock sample is

(a) 38 × 106 years
(b) 48 × 106 years
(c) 38 × 107 years
(d) 48 × 107 years


Q2. The binding energy of the k-shell electron in a Uranium atom (Z = 92, A = 238) will be modified due to (i) screening caused by other electrons and (ii) the finite extent of the nucleus as follows:

(a) increascs due to (i), remains unchanged due to (i)
(b) decreases due to (i), decreases due to (ii).
(c) increases due to (i), increases due to (i).
(d) decreases due to (i), remains unchanged due to (i).


Q3. In the mixture of isotopes normally found on the earth at the present time, 92U238 has an abundance of 99.3% and 92U235 has an abundance of 0.7%. The measured lifetimes of these isotopes are 6.52 × 109 years and 1.02 × 109 years, respectively. Assuming that they were equally abundant when the earth was formed, the estimated age of the earth, in years, is

(a) 6.0 × 109
(b) 1.0 × 109
(c) 6.0 × 108
(d) 1.0 × 108


Q4. The hale-life of a radioactive nuclear source is 9 days. The fraction of nuclei which are let undecayed after 3 days is

(a) 7/8
(b) 1/3
(c) 5/6
(d) 1/21/3


Q5. An alpha particle of energy E is shot towards a gold nucleus (79Au197). At the distances much larger than the nuclear size RN, the dominant force is the Coulomb repulsion, but at distances comparable to the nuclear size the dominant force is the strong nuclear attraction. These combine to form a potential barrier of height Vc .If E < Vc the probability that the alpha particle will fuse with the gold nucleus can be written (in terms of a dimensionless positive constant k) as

(a) Zero
(b) kE/√[k2E2 + (Vc)2]
(c) k(1-E/Vc)
(d) exp(-kVc/E)


Q6. It is well-known that the energy of the Sun arises from the fusion of hydrogen nuclei (protons) inside the core of the Sun. This takes place through several mechanisms, each resulting in emission of energy. Which of the following reactions is NOT possible during the proton fusion inside the Sun?

(a) 1H1 + 1H12He2
(b) 1H2 + 1H12He3
(c) 1H1 + 1H11He2 + e+ +ve
(d) 1H1 + 1H1 + 1H1 + 1H11He4 + 2e+


Q7. Consider a process in which atoms of Actinium-226 (89Ac226) get converted to atoms of Radium-226 (88Ra226) and the yield of energy is 0.64 MeV per atom. This occurs through

(a) Both p → n + e+ + ve and p + e → n + ve
(b) Both p → n + e+ + ve and n → p + e + v’e
(c) Only p → n + e+ + ve
(d) Only p + e → n + ve


Q8. The binding energy per nucleon for 235U is 7.6 MeV. The 235U nucleus undergoes fission to produce two fragments, both having binding energy per nucleon 8.5 MeV. the energy released, in Joules, from the complete fission of 1 kG of 235U is therefore,

(a) 1013
(b) 7.7 × 1013
(c) 5 × 108
(d) 8.7 x 1013


Q9. Two spherical nuclei have mass numbers 216 and 64 with their radii R1 and R2 respectively. The ratio R1/R2 is

(a) 1.0
(b) 1.5
(c) 2.0
(d) 2.5


Q10. A proton is accelerated to a high energy E and shot at a nucleus of Oxygen (8O16) . In order to penetrate the Coulomb barrier and reach the surface of the Oxygen nucleus, E must be at least

(a) 3.6 MeV
(b) 1.8 MeV
(c) 45 keV
(d) 180 eV


Q11. In a nuclear reactor, Plutonium (94Pu239) is used as fuel, releasing energy by its fission into isotopes of Barium (54Ba146) and Strontium (38Sr91) through the reaction

94Pu239 + 0n156Ba146 + 38Sr91 +3 × 0n1

The binding energy (B.E.) per nucleon of each of these nuclides is given in the table below:

Nuclide94Pu23956Ba14638Sr91
B.E. per nucleon (MeV)7.68.28.6

Using this information, one can estimate the number of such fission reactions per second in a 100MW reactor as

(a) 3.9 × 1018
(b) 7.8 × 1018
(c) 5.2 × 1018
(d) 5.2 × 1018


Q12. Let EN be the energy released when one mole of pure 235U undergoes controlled fission, and Ec be the energy released when one mole of pure carbon undergoes complete combustion. The ratio EN/Ec will have the order of magnitude

(a) 104
(b) 108
(c) 109
(d) 106


Q13. A particle P, of rest mass M and energy E, suddenly decays into two particles A and B of rest masses mA and mB respectively, and both particles move along the straight line in which P was moving, A possible energy EA of the particle A will be

(a) E/2 [1 + {(mA – mB)/M}2]
(b) E/2 [1 – {(m2A – m2B)/M2}2]
(c) E/2 [1 + {(mA + mB)/M}2]
(d) E/2 [1 + {(m2A – m2B)/M2}2]


Q14. If Me, Mp, and MH are the rest masses of electron, proton and hydrogen atom in the ground state (with energy -13.6 eV), respectively, which of the following is exactly true? (c is the speed of light in free space)

(a) MH = Mp + Me
(b) MH = Mp + Me13.6 eV/c2,
(c) MH = Mp + Me + 13.6 eV/c2
(d) MH = Mp + Me + K, where K ≠ 13.6 eV/c2 or zero.


Q15.The activity of a radioactive sample is decreased to 75% of the initial value after 30 days. The half-life (in days) of the sample is approximately [You may use In3 ≈ 1.1, In 4 ≈ 1.4]

(a) 38
(b) 45
(c) 59
(d) 69


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Answer Key (if you find any answer wrong, feel free to Correct us)

01.(a)06.(d)11.(a)
02.(b)07.(d)12.(d)
03.(a)08.(d)13.(d)
04.(d)09.(b)14.(b)
05.(d)10.(a)15.(d)

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