Question 51 : If 4 gm of a radioisotope has a half life period of 10 days, the half life of 2 gm of the same istotope will be __________ days.
1. 10
2. 5
3. 30
4. 20
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Question 52 : Pick out the wrong statement.
1. The nucleus of a hydrogen atom is identical with a proton.
2. A, β-ray particle is identical with an electron.
3. Mass of an electron is about 1/1800th of the lightest nucleus.
4. Positron is heavier than a proton.
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Question 53 : Specific gravity of uranium and plutonium is about
1. 9
2. 19
3. 13
4. 27
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Question 54 : The function of moderators in nuclear reactor is to
1. control the chain reaction.
2. absorb the secondary neutrons.
3. slow down the secondary neutrons.
4. none of these.
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Question 55 : Which of the following is not used as a nuclear fuel cladding material ?
1. Zircalloy
2. Cadmium
3. Ceramics
4. Stainless steel
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Question 56 : 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 ?
1. A- Z
2. A+Z
3. A
4. Z
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Question 57 : Which of the following types of nuclear reactors is most prone to radioactive hazards ?
1. Molten sodium cooled reactor
2. Gas cooled reactor
3. Pressurised water reactor
4. Boiling water reactor
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Question 58 : Thermal neutrons which are used to cause the fission of U-235 have energy __________ eV.
1. < 0.025
2. > 200.
3. >1
4. 1-25
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Question 59 : Thermal nuclear reactors using enriched uranium as fuel contains a maximum of __________ percent fissile material i.e. U-235.
1. 2
2. 1
3. 3
4. 6
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Question 60 : A boiling water reactor is the one, in which the
1. coolant water is allowed to boil in the core of the reactor.
2. fuel and the coolant are thoroughly mixed to form a homogeneous solution.
3. coolant water, after being heated in the reactor core, generates steam in a boiler.
4. pressurised water is pumped into the core.
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