The half-life to a radioactive nucleus is 50 days. The time inte

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 Multiple Choice QuestionsMultiple Choice Questions

121.

The scientist who is credited with discovery of 'nucleus' in an atom is

  • Rutherford

  • Niels Bohr

  • Balmer

  • J J Thomson


122.

In nuclear fission the percentage of mass converted into energy is about

  • 0.01 %

  • 10 %

  • 1 %

  • 0.1 %


123.

The SI unit of radioactivity is

  • Rutherford

  • Roentgen

  • Becqueral

  • Curie


124.

In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life ?

  • 63 %

  • 69.3 %

  • 37 %

  • 50 %


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125.

If radius of the Al presubscript 13 presuperscript 27 nucleus is taken to be RAl, then the radius of Te presubscript 53 presuperscript 125 nucleus is nearly

  • open parentheses 53 over 13 close parentheses to the power of 1 third end exponent straight R subscript Al
  • 5 over 3 straight R subscript Al
  • 3 over 5 straight R subscript Al
  • 3 over 5 straight R subscript Al
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126.

When an alpha particle of mass m moving with velocity v bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on mass as,

  • fraction numerator 1 over denominator square root of straight m end fraction
  • 1 over straight m squared
  • m

  • m

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127.

The half-life to a radioactive nucleus is 50 days. The time interval (t2-t1) between the time t2 when 2/3 of  it has decayed and the time t1 when 1/3 of it had decayed is

  • 30 days

  • 50 days

  • 60 days

  • 15 days


B.

50 days



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128.

If the nuclear radius of27 Al is 3.6 Fermi, the approximate nuclear radius of 64Cu in Fermi is

  • 2.4

  • 1.2

  • 4.8

  • 4.8

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129.

A mixture consists of two radioactive materials A1 and A2 with half-lives of 20 s and 10 s respectively. Initially, the mixture has 40 g of A1 and 160 g of A2. The amount of the two in the mixture will become equal after

  • 60 s

  • 80 s

  • 20 s

  • 20 s

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130.

The binding energy per nucleon of Li presubscript 3 presuperscript 7 space and space He presubscript 2 presuperscript 4 nuclei are 5.60 MeV and 7.06 MeV, respectively. In the nuclear reaction, Li presubscript 3 presuperscript 7 space plus space straight H presubscript 1 presuperscript 1 space rightwards arrow space He presubscript 2 presuperscript 4 space plus space straight Q, the value of energy Q released is,

  • 19.6 MeV

  • -2.4 MeV

  • 8.4 MeV

  • 8.4 MeV

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