Tag: nuclear physics

Questions Related to nuclear physics

What is the order of the temperature at which average kinetic energy of an atom in gaseous hydrogen becomes equal to the binding energy of the electron in hydrogen atom?

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

  1. $10^{4}$ K

  2. $10^{5}$ K

  3. $10^{3}$ K

  4. $10^{2}$ K

Show answer
Correct Option: B
Explanation:

Let the temperature be $T$.

So, the K.E. of an atom is gaseous hydrogen is $3kT/2$
where $k=1.38\times10^{-23}$ is the boltzmann constant.
Now the binding energy of the electron in hydrogen atom is $13.6eV=13.6\times1.6\times10^{-19}\ J$
Equating Binding energy and the kinetic energy we get, 
$T=1.004\times10^5\ K$
So temperature is of order of $10^5\ K$

The ratio $r$ of the rate of production of neutrons from uranium nucleus to the rate of leakage of neutrons for sustained chain reaction is 

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

  1. $r>1$

  2. $1>r$

  3. $1>r^{2}$

  4. $r^{2}$ = $1$

Show answer
Correct Option: A
Explanation:
For sustained chain reaction neutron produced during fission must be more than the rate of leakage of neutrons.

Thermal neutrons are those which

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

  1. are at very high temperature

  2. move with high velocities

  3. have kinetic energies similar to those of the surroundings molecules

  4. are at rest

Show answer
Correct Option: C
Explanation:

Thermal neutrons are slow down having kinetic energies similar to those of the surroundings molecules.

The number of fissions of $^{235}U _{92}$ required to a produce a power of $1\ W$ is :

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

  1. $3.1\times 10^{10}$

  2. $3.1\times 10^{13}$

  3. $3.1\times 10^{19}$

  4. $3.1\times 10^{8}$

Show answer
Correct Option: A

State two safety measures to be taken while establishing a nuclear power plant.

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

  1. Use uranium rod and inside environment is not shielded

  2. Use uranium rod and inside environment should be shielded

  3. Use copper rod and inside environment is not shielded

  4. None of the above

Show answer
Correct Option: B
Explanation:
$\rightarrow$ The nuclear energy can turn into the strong blast due to exponential growth in its reaction process. We use Uranium rods to control the reaction.
$\rightarrow$ The inside environment must be shielded from outside because its reaction with water & air causes potential health hazard.

A proton and a neutron are both shot at $100 ms^{-1}$ towards a $ _6^{12}C$ nucleus. Which particle, if either, is more likely to be absorbed by the nucleus?

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

  1. The proton

  2. The neutron

  3. Both particles are about equally likely to be absorbed

  4. Neither particle will be absorbed

Show answer
Correct Option: B
Explanation:

Proton will be experiencing repulsive forces because of presence of positive charges in the nucleus.
Hence, nucleus is more likely to be absorbed.

Fast neutrons can easily be slowed down by

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

  1. the use of lead shielding

  2. passing them through water

  3. elastic collision with heavy nuclei

  4. applying a strong electric field

Show answer
Correct Option: B
Explanation:
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.

What is the purpose of Boron rods in a nuclear reactor ?

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

  1. Absorb excess neutrons

  2. Absorb alpha particles

  3. Slow down the speed of neutrons

  4. Speed up the reaction

Show answer
Correct Option: A
Explanation:

Boron rods are used as control rods in nuclear reactors to control the fission rate of uranium and plutonium. These are capable of absorbing many neutrons without fissioning themselves. Composition of control rods is designed for the neutron spectrum of the reactor.

Control rods in a nuclear power plant is to

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

  1. Slow the neutrons thereby controlling the fission reaction.

  2. Shut down the reactor.

  3. Both $(1)$ and $(2)$

  4. None of these

Show answer
Correct Option: A
Explanation:

Slow the neutrons thereby controlling the fission reaction.


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

Scientists are working hard to develop nuclear fusion reactor. Nuclei of heavy, $ _{ 1 }^{ 2 }{ H }$, known as deuteron and denoted by D, can be thought of as a candidate for fusion reactor. The D-D reaction is  $ _{ 1 }^{ 2 }{H }+ _{ 1 }^{ 2 }{ H }\rightarrow _{ 2 }^{ 3 }{ He+n+energy }$. In the core of fusion reactor, a gas of heavy hydrogen is fully ionized into deuteron nuclei and electrons.This collection of $ _{ 1 }^{ 2 }{ H }$ nuclei and electron is known as plasma. The nuclei move randomly in the reactor core and occasionally come close enough for nuclear fusion to take place. Usually, the temperatures in the reactor core plasma. Special techniques are used which confine the plasma for a time $\displaystyle { t } _{ 0 }$ before the particles fly away from the core. If $n$ is the density (number/volume) of deuterons, the product ${ nt } _{ 0 }$  is called Lawson number, In one of the criteria, a reactor is termed successful if Lawson number is greater than $5 \times { 10 }^{ 14}s/{ cm }^{3 }$. It may be helpful to use the following: Boltzmann constant 

$k=8.6\times { 10 }^{ -5 }eV/K$; $\displaystyle \frac { { e }^{ 2 } }{ 4\pi { \epsilon } _{ 0 } } =1.44\times { 10 }^{ -9 }eVm$. In the core of nuclear fusion reactor. the gas becomes plasma because of :

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

  1. strong nuclear force acting between the deuterons

  2. coulomb force acting between the deuterons

  3. coulomb force acting between deuteron-electron pairs

  4. the high temperature maintained inside the reactor core

Show answer
Correct Option: D
Explanation:

The temperature inside the core of nuclear reactor is so high that the gas of heavy hydrogen used becomes the fourth state of matter which we call as plasma.