If Mo is the mass of an oxygen isotope 8O17 , MP and Mn are the m

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171.

Fission of nuclei is possible because the binding energy per nucleon in them

  • increases with mass number at high mass numbers

  • decreases with mass number at high mass numbers

  • increases with mass number at low mass numbers 

  • decreases with mass number at low mass numbers


172.

In any fission process the ratio Mass of parent nucleusMass of fission products is

  • less than 1

  • greater than 1

  • greater than 1

  • depends on the mass of parent nucleus


173.

In radioactive decay process, the negatively charged emitted -particles are 

  • the electrons present inside the nucleus

  • the electrons produced as a result of the decay of neutrons inside the nucleus

  • the electrons produced as a result of collisions between atoms

  • the electrons orbiting around the nucleus


174.

Two radioactive substances A and B have decay constants 5 λ and λ respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be 1e2 after a time interval

  • 14λ

  • 12λ


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175.

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

  • ( Mo - 8 MP ) c2 

  • ( Mo - 8 MP - 9 Mc ) c2

  • Mo C2

  • (Mo - 17 Mn ) c2


B.

( Mo - 8 MP - 9 Mc ) c2

Binding energy:- If a certain number of protons and neurons are brought together to form a nucleus to form a nucleus of a certain charge and mass, an energy Eb will be released in the process. The energy Eb is called the binding energy of the nucleus.

BE = ( Mnucleus - Mnucleons ) c2

BE = (Mo - 8MP - 9 Mn ) c2


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176.

Hydrogen bomb is based upon

  • fission

  • fusion

  • chemical reaction

  • transmutation


177.

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


178.

Half-lives of two radioactive substances A and B are respectively 20 min and 40 min. Initially the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is

  • 1 : 16

  • 4 : 1

  • 1 : 4

  • 1 : 1


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179.

The half-life of a radio-isotope is 4h. 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


180.

If 82U238 emits 8 α - particles and 6 β - particles, then the resulting nucleus is

  • 82U206

  • 82Pb206

  • 82U210

  • 82U214


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