Assertion:  It is desirable to slow down fast moving ne

Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

221.

S32 absorbs energy and decays into which element after two α-emissions?

  • Carbon

  • Aluminium

  • Oxygen

  • magnesium


222.

Among the following which is used to control the rate of reaction of nuclear fissions reactions?

  • Water

  • Heavy water

  • Cadmium

  • Graphite


223.

Assertion:  For nuclear reactor, it is desirable to have k = 1.

Reason: Sustained chain reaction occur at this critical condition.

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

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

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


224.

Assertion: Mass defect in nuclear reactions is less than 1%.

Reason: In nuclear reaction change in BE/N is generally less than 1%.

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

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

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


Advertisement
225.

Assertion:  It is very easy to detect neutrino in nature. 

Reason:  It has high affinity to interact with matter.

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

  • If both asertion and reason are true and reason is not correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


Advertisement

226.

Assertion:  It is desirable to slow down fast moving neutrons to sustain controlled chain reactions. 

Reason:  Slow moving neutrons efficiently collides with  U235.

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

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

  • If assertion is true but reason is false.

  • If assertion and reason are false.


C.

If assertion is true but reason is false.

The  average  energy  of  a neutron  produced  in fission of  U235 is 2 MeV. These neutrons  unless  slowed  down will escape from  the reactor  without  interacting with  uranium  nuclei, unless  a large  amount  of  fissionable material is used for sustaining the chain reaction.  What we needs to do is to slow down the fast neutrons by elastic scattering with light nuclei.  Chadwick's experiment showed that in an elastic collision with hydrogen neutron almost come to rest.


Advertisement
227.

Two radioactive substances A and 8 have decay constants 5A and A respectively. At I =0, they have the same number of nuclei. The ratio of number of nuclei of A to those of 8 will be (1/e2 ) after a time

  • 12λ

  • 14λ


228.

The intensity of gamma radiation from a given source is  I.  On passing through 36 mm of lead, it is reduced to l/8. The thickness of lead which will reduce the intensity to l/2  will be

  • 18 mm

  • 12 mm

  • 6 mm

  • 9 mm


Advertisement
229.

What is the ratio of Bohr magnetron to the nuclear magnetron?

  • mp/me

  • mp2 / me2

  • 1

  • memp


230.

A nucleus of mass number 220 decays by α decay. The energy released in the reaction is 5 MeV. The kinetic energy of an α-particle is

  • 154MeV

  • 2711 MeV

  • 5411 MeV

  • 5554 MeV


Advertisement