Physics · Science General

Nuclear Physics and Energy

1,296 Questions

Access a comprehensive set of questions on nuclear physics, reactor mechanisms, and atomic energy. Topics include nuclear fission, plasma generation, and radiation control. These physics questions form a core part of the syllabus for various engineering and civil service exams.

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Nuclear Physics and Energy Questions

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Boron rods in a nuclear reactor are used to 

  1. absorb excess neutrons

  2. absorb alpha particle

  3. slow down the reaction

  4. speed up the reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
When a neutron collides with the uranium atom, then energy is released along with three more neutrons which further collide with another uranium atom an so the chain reaction continues. Thus boron rods in nuclear reactor are used to absorb excess neutrons so that the reaction rate remains under control.  
Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Control rods used in nuclear reactors are made of

  1. stainless steel

  2. graphite

  3. cadmium

  4. plutonium
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Control rods are used in the nuclear reactor to control the fission rate of uranium and plutonium. These are composed of chemical elements such as cadmium, silver and indium that are capable of absorbing many neutrons without  fissioning themselves.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

In a nuclear reactor, moderators slow down the neutrons which come out in a fission process.The moderators used have light nuclei. Heavy nuclei will not solve the purpose, because

  1. The net weight of the reactor would be unbearably high.

  2. Heavy nuclei will break generating unwanted smaller nuclei.

  3. Elastic collision of neutrons with heavy nuclei will not slow them down.

  4. Substances with heavy nuclei do not occur in liquid or gaseous state at room temperature.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In an elastic collision, kinetic energy is transferred most efficiently when the masses of the colliding particles are similar. If a neutron hits a heavy nucleus, it bounces off with almost all its original energy, failing to slow down.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Heavy water is used in nuclear reactor as _________.

  1. Coolant

  2. Moderator

  3. Both coolant and moderator

  4. Catalyst
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both coolant and moderator.

Heary water ( $D _20$ )  also called deuterium oxide, water composed of deuterium, the hydrogen isotope with a mass double that of ordinary hydrogen and oxygen. The heary water is used as a moderator of neutrons and also as a coolent in nuclear power plants.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

What is the importance of moderator in a nuclear reactor?

  1. Moderator controls the flow of water inlet.

  2. Controls the nuclear fission by absorbing the excess neutrons.

  3. Controls the nuclear fission by slowing down the neutrons.

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Controls the nuclear fission by slowing down the neutrons.


A moderator is a material used on a nuclear reactor to slow down the neutrons produced from fission. By slowing down neutrons the probability of a neutron interacting with Uranium-235 nuclei is greatly increased thereby maintaining the chain reaction. Carbon in the form of graphite is commonly used as a moderator.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Which is the material responsible for controlling the chain reaction in nuclear reactor?

  1. Boron

  2. Zirconium

  3. Beryllium

  4. Lead
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Beryllium

Beryllium is considered to be a basically an excellent material fir moderators and reflectors in nuclear reaction, because of its nuclear properties and many of its other physical and mechanical properties.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

In a nuclear reactor, it is desirable to use reactor core in the form of ____________.

  1. cubical or cylindrical

  2. cubical or spherical

  3. cylindrical or spherical

  4. spherical
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a nuclear reactor core from a physical standpoint, the best reactor core shape is a sphere, but design considerations often dictate a cylindrical shape.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

In nuclear reactor, graphite is used as ___________.

  1. Fuel

  2. Coolant

  3. Moderator

  4. Electrode
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving U-235 or a fissile nuclide. Graphite is used as moderator in nuclear reactor.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

In a nuclear reactor, nuclear energy is obtained by breaking the nucleus of uranium by :

  1. fast moving neutrons

  2. fast moving electrons

  3. slow moving electrons

  4. slow moving neutrons
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

D

In fission each nucleus of uranium -235 emits on an average more than two neutrons. If one of these two neutrons is absorbed by another uranium -235 nucleus, causing it to fission, thus we can have a sustainable chain reaction. However, only a slow neutron, rather than a fast neutron has a high cross section( chance) of absorption. That is why slow moving neutrons are used.