Tag: the nuclear power station

Questions Related to the nuclear power station

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}$

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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. $Th^{236}$

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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 :

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

  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.

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

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

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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

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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. $3.1\times 10^{8}$

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Correct Option: A