1) Which of the following is a moderating material used in nuclear reactor ? a. Graphite b. Cadmium c. Zircaloy (an alloy of zirconium and aluminium) d. Stainless steel
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2) Nuclear reactors are provided with shield to guard against the emission of mainly _____________ rays? a. X b. α and β c. Neutrons & gamma d. Infrared
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3) The amount of a radioisotope remaining undecayed after a time equal to four times its half life, will be _____________ percent? a. 3.125 b. 6.25 c. 12.50 d. 25
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4) Out of the following, nucleus of _____________ atom contains the largest number of neutrons? a. U-235 b. U-238 c. U-239 d. Pu-239
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5) Molten sodium (as a coolant in fast breeder reactor) ? a. Can’t attain high temperature at normal pressure b. Is not at all corrosive, even at a higher temperature c. Is highly radioactive at elevated temperatures and can cause explosion, when it comes in contact with air or water d. None of these
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6) Commercial power generation from fusion reactor is not yet possible, because___________________? a. It is difficult to control nuclear fusion reaction b. The fuel required (i.e., deuterium & tritium) is scarce c. It is difficult to initiate fusion reaction d. Quantity of fuel required for initiating fusion reaction is prohibitively high
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7) Thermal shield is used in high powered nuclear reactors to__________________? a. Protect the walls of the reactor from radiation damage b. Absorb the fast neutrons c. Slow down the secondary neutrons d. Protect the fuel element from coming in contact with the coolant
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8) A radioactive substance does not emit________________? a. α-ray b. Proton c. Position d. β-ray
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9) The ratio of neutrons to protons of an element having a mass number and atomic number of 80 and 40 respectively is ___________________? a. 1 b. 0.5 c. 2 d. 4
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10) Coolant used in a boiling water reactor is________________? a. Hydrogen gas b. Water c. Steam d. A mixture of water & steam
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11)
The 92U238 emits an a-particle. The product is____________________? a. 90U234 b. 90U238 c. 90U236 d. 92U236
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12) Percentage of the heavy water in ordinary water is around ____________________? a. 0.015 b. 7.54 c. 0.71 d. 32.97
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13) Which is the most commonly used molten metal for cooling of nuclear reactors ? a. Calcium b. Sodium c. Mercury d. Zinc
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14) Energy produced in the nuclear fission is of the order of _____________ MeV? a. 20 b. 200 c. 1000 d. 2000
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15) _____________ have the same mass number, but different nuclear charge ? a. Isotopes b. Isobars c. Isotones d. None of these
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16) The mass number of an element is equal to the number of _____________ in the nucleus? a. Electrons b. Neutrons c. Protons d. Neutrons plus protons (i.e., nucleons)
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17) Radioactive decay is a _____________ change? a. Chemical b. Nuclear c. Physical d. None of these
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18) The atomic number of an element is equal to the number of ______________ present in its atom? a. Neutrons b. Electrons c. Protons d. Either B. or C.
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19) “Critical mass” is the minimum mass of nuclear fissile material required for the__________________? a. Sustainment of chain reaction b. Power generation on commercial scale c. Economic power generation d. None of these
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20) The atomic mass of an element is fractional, because ______________________? a. Of uncertainty principle b. It may have isobars c. It contains neutrons d. It may have isotopes
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