Practice Test: Question Set - 15
1. A radioactive substance does not emit
- (A) α-ray
- (B) Proton
- (C) Positron
- (D) β-ray
2. Which of the following nuclear materials is fissile?
- (A) Uranium-238
- (B) Thorium-232
- (C) Plutonium-239
- (D) None of these
3. 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
4. Gas cooling as compared to water cooling of nuclear reactors
- (A) Cannot attain a high temperature
- (B) Is more efficient as gas has a higher specific heat
- (C) Can produce only saturated steam for feeding to power turbine
- (D) None of these
5. Pick out the wrong statement.
- (A) The disintegration rate of a radioactive substance cannot be
increased by heating it
- (B) Electrons have negligible mass and unit negative change
- (C) Deuterium atom has one proton and two neutrons
in its nucleus
- (D) Cadmium is capable of absorbing neutrons
6. Unit of radioactivity is
- (A) Barn
- (B) Fermi
- (C) Angstrom
- (D) Curie
7. 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
8. The velocity of thermal (slow) neutrons triggering nuclear fission reaction (having energy equal to 0.025 eV) is about __________ meters/second.
- (A) 1100
- (B) 2200
- (C) 3300
- (D) 4400
9. 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
10. Positron is a/an
- (A) Nucleus having two protons
- (B) Helium nucleus
- (C) Electron with positive charge
- (D) Nucleus with one proton and one neutron
11. 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
12. Nuclear power reactor located at Tarapur is of __________ type.
- (A) Fast breeder
- (B) Pressurized water
- (C) Boiling water
- (D) Gas cooled
13. 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
14. Quantity of fissionable material (i.e. U-235) in natural uranium is __________ percent.
- (A) 0.71
- (B) 6.31
- (C) 99.29
- (D) 12.73
15. 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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