Q.1
Use of molten metal as a coolant in fast breeder reactor helps in
Q.2
Fuel for a fast breeder reactor is
Q.3
Which of the following is the most harmful for the human being?
Q.4
Coolant used in a boiling water reactor is
Q.5
The atomic weight and atomic number of an element are A and Z respectively. What is the number of neutrons in the atom of that element?
Q.6
__________ have the same mass number, but different nuclear charge.
Q.7
Water is a better coolant than a gas (like CO₂, He, N₂ etc.), because it
Q.8
Which of the following gases has very high neutron capture cross-section, making it unsuitable as a coolant in nuclear reactor?
Q.9
When the difference between mass number and atomic number of atoms of two or more elements are same, the atoms are termed as
Q.10
Uranium is recovered from its ore (pitchblende) by
Q.11
The time taken for a radioactive element to reduce to 50% of its original weight is __________ years, if its half life period is 12 years.
Q.12
Extraction of uranium from its ore is done by __________ method.
Q.13
Graphite is used in nuclear reactor as
Q.14
Which is the most commonly used molten metal for cooling of nuclear reactors?
Q.15
Radioactive decay is a __________ change.
Q.16
Heavy water (D₂O) in a nuclear reactor serves as a
Q.17
Moderating material used in a thermal-reactor should be a
Q.18
Which of the following is not an ore of uranium?
Q.19
Heavy water used in the nuclear reactors to slow down the speed of neutrons is
Q.20
The sum of masses of two nuclei produced in nuclear fission compared to the mass of original nucleus is
Q.21
75% of a radioactive element decays in 6 hours. Its half life period is __________ hours.
Q.22
Pick out the wrong statement.
Q.23
The 92U238 emits an a-particle. The product is
Q.24
Nuclear fuel generally used in reactors is uranium oxide instead of uranium, because the former has higher
Q.25
Which of the following may not need a moderator?
Q.26
Which one is the radioactive isotope of hydrogen?
Q.27
Pick out the correct statement.
Q.28
Heavy water has maximum density at __________ °C.
Q.29
Main source of __________ is monazite sand.
Q.30
The phenomenon of nuclear fission is opposite to that of
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