92U235 undergoes successive disintegrations with the en

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 Multiple Choice QuestionsMultiple Choice Questions

81.

The volume of a nucleus is directly proportional to

  • A

  • A3

  • A

  • A1/3


82.

An electron is

  • a hadron

  • a baryon

  • a nucleon

  • a lepton


83.

Two protons are kept at a separation of 40 A. Fn is the nuclear force and Fe is the electrostatic force between them. Then

  • Fn >> Fe

  • Fn = Fe

  • Fn << Fe

  • Fn ≈ Fe


84.

The ratio of the nuclear radii of elements with mass numbers 216 and 125 is

  • 216 : 125

  • 216 : 125

  • 6 : 5

  • None of these


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85.

On bombarding U235 by slow neutron, 200 MeV energy is released. If the power output of atomic reactor is 1.6 MW, then the rate of fission will be

  • 5 × 1022/s

  • 5 × 1016/s

  • 8 × 1016/s

  • 20 ×1016/s


86.

The masses of two radioactive substances are same and their half-lives are 1 yr and 2 yr respectively. The ratio of their activities after 4 yr will be

  • 1 : 4

  • 1 : 2

  • 1 : 3

  • 1 : 6


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87.

92U235 undergoes successive disintegrations with the end product of 82Pb203. The number of α and β particles emitted are

  • α = 6, β = 4

  • α = 6, β = 0

  • α = 8, β = 6

  • α = 3, β = 3


C.

α = 8, β = 6

Let number of α particles decayed be x and number of β particles decayed be y.

Then equation for the decay is given by

U23592  24 + γβ-10 + Pb82203    

Equating the mass number on both sides

235 = 4x + 203                             ....... (i)

Equating atomic number on both sides

 92 = 2x − y + 82                          ....... (ii)

Solving Eqs. (i) and (ii), we get

x = 8, y = 6

∴ 8α particles and 6β particles are emitted in disintegration.


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88.

The most stable particle in Baryon group is

  • neutron

  • omega-particle

  • proton

  • lambda-particle


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89.

In a radioactive disintegration, the ratio of initial number of atoms to the number of atoms present at an instant of time equal to its mean life is

  • 1e2

  • 1e

  • e

  • e2


90.

β- decay means emission of electron from

  • innermost electron orbit

  • a stable nucleus

  • outermost electron orbit

  • radioactive nucleus


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