Which one of the following is used as a moderator in nuclear reac

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

Advertisement

291.

Which one of the following is used as a moderator in nuclear reaction?

  • Uranium

  • Heavy water

  • Cadmium

  • Plutonium


B.

Heavy water

Heavy water is deuterium oxide or D2or 2H2O. It is used in certain types of nuclear reactors, where it acts as a neutron moderator to slow down neutrons so that they can react with the uranium in the reactor. Because heavy water reactor can be natural uranium, it is of concern in efforts to prevent nuclear proliferation.


Advertisement
292.

The Kα line from molybdenum (atomic number = 42) has a wavelength of 0.7078 A. The wavelength of Kα line of zinc (atomic number = 30) will be

  • A

  • 1.3872 A

  • 0.3541 A

  • 0.5 A


293.

Decay constant of radioactive element is 1.5 × 10-9/s. Average age of element is

  • 1.5 × 109

  • 4.62 × 108

  • 6.67 × 108

  • 10.35 × 108


294.

Half-life of radium is 1600 yr, then its 1/16th part will remain undecayed after

  • 1200 yr

  • 6400 yr

  • 1800 yr

  • 2200 yr


Advertisement
295.

Atomic number of an atom is Z and mass number is m, then number of neutrons in its nucleus is

  • m − Z

  • mZ

  • m + Z

  • m × Z


296.

Nucleus of an atom has

  • e and n

  • e and p

  • p and n

  • e, p and n


297.

A nucleus undergoes β-decay. The mass number and  atomic number change as

  • mass number and atomic number both increases

  • mass number remain same and atomic number increases

  • mass number increases and atomic number remain same

  • mass number and atomic number both decreases


298.

When a radioactive isotope Ra22888 decay in series by the emission of 3α -particles and a β -particle, the isotope finally formed is

  • X21682

  • X21583

  • X21688

  • X21683


Advertisement
299.

The activity of a radioactive element decreases to one third of the original activity I0 , in a period of 9 years. After a further lapse of 9 years, its activity will be

  • I0

  • (2/3) I0

  • I0 / 9

  • I0 / 6


300.

If Mo is the mass of an oxygen isotope O178, Mp and Mn are the masses of a proton and a neutron, respectively, the nuclear binding energy of the isotope is

  • (Mo − 8Mp) c2

  • (Mo − 8Mp − 9Mn) c2

  • Moc2

  • (Mo − 17Mn) c2


Advertisement