Tag: nuclear physics

Questions Related to nuclear physics

During a nuclear fission reaction 

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  1. a heavy nucleus breaks into two fragments by itself

  2. a light nucleus bombared by thermal neutrons breaks up

  3. a heavy nucleus bombared by thermal neutrons breaks up

  4. two light nuclei combine to give a heavier nucleus and possibly other products

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Correct Option: C
Explanation:
In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts, and reaction is triggered by neutron bombardment.

The fissionable material used in a breeder reactor is ________

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

  1. $ _{92}\textrm{U}^{235}$

  2. $ _{94}\textrm{Pu}^{239}$

  3. $ _{90}\textrm{Th}^{234}$

  4. $ _{c}\textrm{C}^{12}$

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Correct Option: B
Explanation:

Non-fissionable uranium-238 is 140 times more abundant than the fissionable U-235 and can be efficiently converted into Pu-239 by the neutrons from a fission chain reaction.

Atomic reactor is based on 

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  1. controlled chain reaction

  2. uncontrolled chain reaction

  3. nuclear fission

  4. nuclear fusion

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Correct Option: C
Explanation:

All commercial reactor is based on nuclear fission. An atomic reactor means a great explosion of power that results come from a nuclear fission reaction of heavy nuclei (uranium, plutonium). 

The critical mass of $U^{235}$ can be reduced by 

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

  1. putting a neutron reflector around it

  2. heating it

  3. mixing impurity in it

  4. putting neutron absorber around it

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Correct Option: A
Explanation:
Surrounding a spherical critical mass with a neutron reflector further reduces the mass needed for criticality. A common material for a neutron reflector is beryllium metal. This reduces the number of neutrons which escape the fissile material, resulting in increased reactivity.

The most suitable material for moderator in a nuclear reactor is 

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

  1. $D _{2}$

  2. $Cd$

  3. $B$

  4. $ _{92}\textrm{U}^{235}$

Show answer
Correct Option: A
Explanation:
In nuclear reactor, 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.
Commonly used moderators include regular (light) water (roughly 75% of the world's reactors), solid graphite (20% of reactors) and heavy water.

Which of the following is the best nuclear fuel?

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

  1. $U^{236}$

  2. $Pu^{239}$

  3. $Np^{239}$

  4. $Th^{236}$

Show answer
Correct Option: B
Explanation:
Plutonium 239 is fissile.
Plutonium 239 is one of the two fissile materials used for the production of nuclear weapons and in some nuclear reactors as a source of energy.

The atomic weight of uranium isotope, which is equally fissionable is :

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  1. $235$

  2. $238$

  3. $234$

  4. $236$

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Correct Option: A
Explanation:
Uranium-235 is an isotope of uranium. It is fissile, i.e., it can sustain a fission chain reaction.

The fission of $U^{238}$ is possible by 

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

  1. only fast neutrons

  2. only slow neutrons

  3. fast as well as slow neutrons

  4. fast protons

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Correct Option: A
Explanation:

Uranium-23, do not usually undergo fission when struck by slow neutrons, but do split when struck with neutrons of high enough energy. The fast neutrons produced in a hydrogen bomb by fusion of deuterium and tritium have even higher energy than the fast neutrons produced in a nuclear reactor. This makes it possible to increase the yield of any given fusion weapon by the simple expedient of adding layers of cheap natural (or even depleted) uranium. Fast fission of uranium-238 provides a large part of the explosive yield, and fallout, in many designs of hydrogen bomb.

For maintaining sustained chain reaction, the following is required

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

  1. protons

  2. electrons

  3. neutrons

  4. positrons

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Correct Option: C
Explanation:
Example : uranium$-235$ atom absorbs a neutron, and fission into two new atoms (fission fragments), releasing three new neutrons and a large amount of binding energy.

In nuclear reactor which of the following quantities is conserved?

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

  1. only energy

  2. only mass

  3. only momentum

  4. mass, energy and momentum

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Correct Option: C
Explanation:
The reason why mass is not being conserved is that mass is being converted to energy
Also we energy can we assume to be conserve if consider change of internal energy.