Q.1

Thorium-(a fertile material) on absorption of a neutron gets converted into __________ , which is a fissile material.

  • thorium-233
  • uranium-235
  • uranium-233
  • plutonium-239
Q.2

A fast breeder reactor

  • uses natural uranium as fuel.
  • does not require a moderator.
  • both (a) and (b).
  • neither (a) nor (b).
Q.3

Heavy water has maximum density at __________ °C.

  • 4
  • 11.6
  • 0
  • 18.6
Q.4

Pick out the wrong statement.

  • Isotopes have the same number of protons & electrons, but different number of neutrons.
  • Hydrogen has two isotopes.
  • In ordinary hydrogen, 1H1 and 1H2 are present in the ratio 6400:1.
  • none of these.
Q.5

Artificially produced radioactive isotopes are used for

  • power generation.
  • treatment of certain diseases.
  • initiating nuclear fission and fusion.
  • all (a), (b) and (c).
Q.6

In a homogeneous nuclear reactor, the __________ are mixed together.

  • fuel & coolant
  • fuel & moderator
  • coolant & moderator
  • none of these
Q.7

Nuclear reactors are provided with shield to guard against the emission of mainly __________ rays.

  • X
  • α and β
  • neutrons & gamma
  • infrared
Q.8

Percentage of heavy water in ordinary water is around

  • 0.015
  • 7.54
  • 0.71
  • 32.97
Q.9

Ceramic nuclear metals compared to solid nuclear metals have

  • higher melting points.
  • low strength at high temperature.
  • more chances of radiation damage.
  • poorer corrosion resistance.
Q.10

The most abundant isotope of natural uranium is

  • 92U238
  • 92U235
  • 92U234
  • none of these
Q.11

Out of the following, nucleus of __________ atom contains the largest number of neutrons.

  • U-235
  • U-238
  • U-239
  • Pu-239
Q.12

Mass of a positron is same as that of a/an

  • electron
  • α-particle
  • proton
  • neutron
Q.13

Biological shield is provided in a nuclear power reactor to protect the __________ from radiation damage.

  • fuel elements
  • operating personnels
  • walls of the reactor
  • none of these
Q.14

Which of the following is not used as a moderator in nuclear reactor ?

  • Molten sodium
  • Light water
  • Beryllium
  • Boron hydride
Q.15

The mass number of an element is equal to the number of __________ in the nucleus.

  • electrons
  • neutrons
  • protons
  • neutrons plus protons (i.e., nucleons)
Q.16

Plutonium

  • is recovered from spent fuel from thermal nuclear reactor.
  • has much lower melting point (640°C ) compared to thorium (1690°C).
  • both (a) and (b).
  • neither (a) nor (b).
Q.17

Secondary cooling circuit is a must in molten sodium cooled fast breeder reactor for

  • achieving high degree of superheat in the steam.
  • faster heat removal rate from the core.
  • lowering the coolant circulation pressure.
  • avoiding the mixing of water with radioactive sodium, as it may cause explosion.
Q.18

H2 is a better coolant than CO2, due to its relatively

  • lower density.
  • higher specific heat.
  • non-reactivity to uranium.
  • lower neutron capture cross-section.
Q.19

Safety rods provided in nuclear reactors to guard against accidents, in case of earthquake are made of

  • high carbon steel.
  • molybdenum.
  • zircalloy.
  • boron or cadmium.
Q.20

Pick out the wrong statement.

  • Atoms with same number of nucleons but different number of protons are called isobars.
  • Atoms with same number of protons but different number of nucleons are called isoters.
  • Out of α, β, and γ-rays, the one having maximum penetration power are γ-rays.
  • The product formed by emission of α-particle has mass number less by 4 units than the parent nuclide.
Q.21

Commercial power generation from fusion reactor is not yet possible, because

  • it is difficult to control nuclear fusion reaction.
  • the fuel required (i.e., deuterium & tritium) is scarce.
  • it is difficult to initiate fusion reaction.
  • quantity of fuel required for initiating fusion reaction is prohibitively high.
Q.22

Fast breeder reactors are most usable in India, because of our largest __________ deposits.

  • thorium
  • plutonium
  • uranium
  • none of these
Q.23

Isotopes of an element have different

  • mass number
  • electronic configuration
  • nuclear charge
  • chemical properties
Q.24

Radioactive decay of a material involves a __________ order reaction.

  • third
  • second
  • first
  • zero
Q.25

In β-decay of radioactive material, the ratio of neutron to proton

  • increases.
  • remains same.
  • decreases.
  • is unpredictable; may increase or decrease.
Q.26

The half life period of a radioactive element depends upon the

  • temperature
  • pressure
  • amount of element present
  • none of these
Q.27

A control rod

  • should have small absorption cross-section.
  • is generally made of boron, hafnium or cadmium.
  • should have large absorption cross-section.
  • both (b) and (c).
Q.28

Number of secondary neutron emitted on fission of an atom of U-by slow neutron bombardment is

  • 3
  • 235
  • 200
  • 92
Q.29

The main purpose of control rod in a nuclear reactor is to control the

  • chain reaction and hence the power output by regulating the number of secondary neutrons causing fission.
  • emission of hazardous radiation.
  • conversion of fissile material into fertile material.
  • velocity of the secondary neutrons.
Q.30

The half life period of a radiactive element isdays. Afterdays, one gm of the element will be reduced to __________ gm.

  • 1/4
  • 1/8
  • 1/2
  • 1/16
0 h : 0 m : 1 s