A neutron makes a head-on elastic collision with a stationar

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 Multiple Choice QuestionsMultiple Choice Questions

261.

A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be

  • 1840 keV

  • 1/1840 keV

  • 1 keV

  • 920 keV


262.

A radioactive substance decays to 1/16th of its initial activity in 40 days. The half-life of the radioactive substance expressed in days is

  • 2.5

  • 5

  • 10

  • 20


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263.

A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is

  • 16/81

  • 8/9

  • 8/27

  • 2/3


B.

8/9

One deuteron consists of one proton and one neutron. As the mass of a proton and a neutron is approximately same (≈ 1.67 × 10-27 kg ), we assume that the mass of the neutron be m and the mass of the deuteron be 2mas the electron mass is negligibly small compared to that of proton and neutron.

Let the initial velocity of the neutron be u. As the deuteron is initially at rest, the final velocity of the neutron is

       

And the velocity of the deutron is

       

Total energy before collision is 

       E1 = 1/2 mu2

After the collision, the energy gained by the deuteron is

      



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264.

Nuclear fusion is possible

  • only between light nuclei

  • only between heavy nuclei

  • between both light and heavy nuclei

  • only between nuclei which are stable against β-decay


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265.

Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called

  • gamma camera

  • CAT scan

  • radiotracer technique

  • gamma ray spectrosccopy


266.

In a material medium, when a positron meets an electron both the particles annihilate leading to the emission of two gamma ray photons. This process forms the basis of an important diagnostic procedure called 

  • MRI

  • PET

  • CAT

  • SPECT


267.

Assertion: Radioactive nuclei emit  β- particles.

Reason: Electrons exist inside the nucleus.

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

  • if both assertion and reason are true and the reason is not the correct explanation of the assertion

  • if assertion is true but reason is false

  • If both assertion and reason are false statements


268.

Assertion: Neutrons penetrate matter more readily as compared to protons.

Reason: Neutrons are slightly more massive than protons.

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

  • if both assertion and reason are true and the reason is not the correct explanation of assertion

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


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269.

Assertion:  Quasar emits radiowaves more than radio galaxy. 

Reason:  Quasar has very small size

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

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

  • If the assertion is true but the reason is false.

  • If both assertion and reason are false.


270.

Mass of the proton is 1840 times that of electron. It is accelerated through a potential difference of 1V. Find its kinetic energy.

  • 6 eV

  • 2 eV

  • 10 eV

  • 1 eV


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