If r1 and r2 are the radii of the atomic nuclei of mass 

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181.

The specific charge of a proton is 9.6 x 107 C/kg. The specific charge of an alpha particle will be

  • 9.6 x107 C/kg

  • 19.2 x 107 C/kg

  • 4.8 x107 C/kg

  • 2.4 x 107 C/kg


182.

Activity of a radioactive sample decreases to (1/3)rd of its original value in 3 days. Then, in 9 days its activity will become

  • (1/27) of the original value

  • (1/9) of the original value

  • (1/18) of the original value

  • (1/3) of the original value


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183.

If r1 and r2 are the radii of the atomic nuclei of mass numbers 64 and 125 respectively, then the ratio ( r1/ r2 ) is

  • 64125

  • 64125

  • 54

  • 45


D.

45

Nucleus of mass number A has a radius   

      R = Ro A13

Atomic mass number A1 =64

              64 13 = 4

Atomic mass number A2 = 125

               12513  = 5

∴        r1r2 = A1A213

              =  453  13

          r1r2 = 45


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184.

the ionization energy of Li2+ is equal to 

  • 9hcR

  • 6hcR

  • 2hcR

  • hcR


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185.

A radioactive element  X23890 decays into Y 22283. The number of β-particles emitted are 

  • 1

  • 2

  • 4

  • 6


186.

The binding energy per nucleon is maximum in the case

  • U92235

  • Ba56141

  • Fe2656

  • He42


187.

The half-life of radio isotope is 4 h. If initial mass of the isotope was 200 g, then mass remaining after 24 h will be

  • 1.042 g 

  • 2.084 g

  • 3.125 g

  • 4.167 g


188.

Remaining quantity (in%) of radioactive element after 5 half lives is

  • 4.125%

  • 3.125%

  • 31.1%

  • 42.125%


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189.

The half-life of 198Au is 2.7 days. The average life is

  • 4 days

  • 3.4 days

  • 3.9 days

  • None of the above


190.

If MO is the mass of an oxygen isotope 8O17 Mp and Mn are the masses of a proton and a neutron, respectively, the nuclear binding energy of the isotope is

  • Mc2

  • ( MO - 17Mn ) c2

  • (MO - 8Mp ) c2

  • ( 8 Mp + 9 Mn - MO)


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