Which one of the following statement is true, if half-life of a r

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 Multiple Choice QuestionsMultiple Choice Questions

51.

The energy released in the fission of 1 kg of 92U235 is (energy per fission = 200 MeV)

  • 5.1 × 1026 eV

  • 5.1 × 1026 J

  • 8.2 × 1013 J

  • 8.2 × 1013 MeV


52.

The nuclear radius of a certain nucleus is 7.2 fm and it has charge of 1.28 x 10-17 C. The number of neutrons inside the nucleus is

  • 136

  • 142

  • 140

  • 132


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53.

Which one of the following statement is true, if half-life of a radioactive substance is 1 month ?

  • 7/8th part of the substance will disintegrate in 3 months

  • 1/8th part of the substance will remain undecayed at the end of 4 months

  • The substance will disintegrate completely in 4 months

  • 1/16th part of the substance will remain undecayed at the end of 3 months


A.

7/8th part of the substance will disintegrate in 3 months

    N N0 = 12n  or  NN0 = 12t/t1/2  or NN0 = 12t/1  For t = 3 months,   NN0 = 123 = 18

Therefore, disintegrated part of substance in 3 months

   = 1 - 18 = 78


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54.

Consider the nuclear reaction X200 → A110 + B80, If the binding energy per nucleon for X, A and B are 7.4 MeV, 8.2 MeV and 8.1 MeV respectively, then the energy released in the reaction is

  • 70 MeV

  • 200 MeV

  • 190 MeV

  • 10 MeV


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55.

The natural boron of atomic weight 10.81 is found to have two isotopes B10 and B11. The ratio of abundance of isotopes in natural boron should be

  • 11 : 10

  • 81 : 19

  • 19 : 81

  • 15 : 16


56.

Radium has a half-life of 5 yr. The probability of decay of a radium nucleus in 10 yr is

  • 50 %

  • 75 %

  • 100 %

  • 60 %


57.

The binding energy per nucleon for deuteron and helium are 1.1 MeV and 7.0 MeV. The energy released when two deuterons fuse to form a helium nucleus is

  • 23.6 MeV

  • 2.2 MeV

  • 30.2 MeV

  • 3.6 MeV


58.

In artificial radioactivity, 1.414 x 106 nuclei are disintegrated into 106 nuclei in 10 min. The half-life in minutes must be 

  • 5

  • 20

  • 15

  • 30


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59.

The half-life of radon is 3.8 days. How many radon will be left out of 1024 mg after 38 days

  • 1 mg

  • 2 mg

  • 3 mg

  • 4 mg


60.

Which of the following is not conserved in nuclear reaction ?

  • Total energy

  • Mass number

  • Number of fundamental particles

  • Nucleon number


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