Which one of the following is a possible nuclear reaction?

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 Multiple Choice QuestionsMultiple Choice Questions

241.

The operation of a nuclear reactor is said to be critical, if the multiplication factor  ( K ) has a value

  • 1

  • 1.5

  • 2.1

  • 2.5


242.

U98238 has  92  protons  and  238  nucleons. It decays by emitting an alpha particle and becomes

  • U92238

  • Th90234

  • U92235

  • Np93237


243.

The foil bone has a 14C : 12C  ratio, which is  [ 1/16 ] of  that in a living animal bone. If the half-life time of  14C  is  5730 years, then the age of the fossil bone is

  • 11460 years

  • 17190 years

  • 22920 years

  • 45840 years


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244.

Which one of the following is a possible nuclear reaction?

  • B510 +  He24   N713  + H11

  • Na1123  +  H11  Ne10 20  +  He24

  • Np93239    Pu94239  +  β-  + ν¯

  • N711 + H11  C612 + β- + ν¯


C.

Np93239    Pu94239  +  β-  + ν¯

According to the conservation of mass number 

         10 + 4 = 13 + 1

According to conservation of charge number

          5 + 2 ≠ 7 + 1

hence (a) is not possible

According to conservation of mass number

        93  = 94 - 1

According to conservation of charge number,

         239 = 239

Hence (c) is not possible

According to conservation of mass number,

       11 + 1 = 12

According to conservation of charge number,

      7 + 1 ≠ 6 - 1

Hence (d) is not possible

Na1123  +  H11  also satisfies both the conservation of mass number and charge. However,  23Na is a very stable isotope and nuclear reaction will be very difficult. The formation of Pu from Np is well known. It satisfies the conditions of conservations and Np is also very unstable. Therefore (c) is the only correct answer.


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245.

If alpha, beta and gamma rays carry same momentum, which has the longest wavelength?

  • Alpha rays

  • Beta rays

  • Gamma rays

  • None, all have same wavelength


246.

Assertion:  The binding energy per nucleon, for nuclei with atomic mass number A > 100 decreases with A. 

Reason:  The nuclear forces are weak for heavier nuclei.

  • If both assertion and reason are true and reason is the correct explanation of the assertion

  • If both assertion and reason are true but reason is not the correct explanation of the assertion

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


247.

Assertion:  Cobalt-60 is useful in cancer therapy. 

Reason:  Cobalt-60 is a source of y-radiations capable of killing cancerous cells.

  • If both assertion and reason are true and reason is the correct explanation of the assertion

  • If both assertion and reason are true but reason is not the correct explanation of the assertion

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


248.

The magnetic moment ( μ) of a revolving  electron around the nucleus varies with principal quantum number n as

  •  μ ∝ n

  •  μ  ∝ 1/n

  •  μ ∝  n2

  • μ ∝ 1/n2


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249.

A radioactive material has a half-life of 10 days. What fraction of the material would remain after 30 days?

  • 0.5

  • 0.25

  • 0.125

  • 0.33


250.

According to Hubble's law, the redshift (Z) of a receding galaxy and its distance r from earth are related as

  • Z ∝ r 

  • Z ∝ 1/r

  • Z ∝ 1/r2

  • Z ∝ r3/2 


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