Tag: nuclear reactions

Questions Related to nuclear reactions

In nuclear reaction
$ _{2}He^{4}+\ _{Z}X^{A}\rightarrow Z+\  _{2}\gamma^{A+3}+\ _{Z}M^{A}$
where $M$ denotes

  1. electron

  2. positron

  3. proton

  4. neutron


Correct Option: D

One milligram of matter converted into energy will give:

  1. $90\ J$

  2. $9\times 10^{3}\ J$

  3. $9\times 10^{10}\ J$

  4. $9\times 10^{3}\ J$


Correct Option: C

A parent nucleus $^{m} _{1}p$ decays into a daughter nucleus $D$ through $\alpha$ emission in the following way $^{m} _{1}p\rightarrow D+\alpha$ The subscript and superscript on the daughter nucleus $D$ will be written as

  1. $^{m} _{n}D$

  2. $^{m+4} _{n}D$

  3. $^{m-4} _{n}D$

  4. $^{m-4} _{n-2}D$


Correct Option: D

Name the following nuclear reaction :
$ _{92}U^{238}(\alpha, 6p, 13n) _{88}Ra^{228}$

  1. particle-particle reaction

  2. capture reaction

  3. fission reaction

  4. separation


Correct Option: D

Consider a hypothetical annihilation of a stationary electron with a stationary positron. What is the wavelength of the resulting radiation?

  1. $\lambda = \displaystyle\frac{h}{2m _ec}$

  2. $\lambda = \displaystyle\frac{2h}{m _ec^2}$

  3. $\lambda = \displaystyle\frac{h}{2m _ec^2}$

  4. None of these


Correct Option: A
Explanation:

Annihilation is the conversion of matter into energy.
Using equation $E={ m } _{ e }{ c }^{ 2 }$
$\dfrac { hc }{ \lambda  } =2{ m } _{ e }{ c }^{ 2 }$
$\Rightarrow \lambda =\dfrac { h }{ { 2m } _{ e }{ c } } $

In which of the following nuclear reactions, the product is incorrectly matched ?

  1. $ _{96}Cm^{242}(\alpha, 2n) _{97}Bk^{243}$

  2. $ _5B^{10}(\alpha, n) _7N^{13}$

  3. $ _7N^{14}(n, p) _6C^{14}$

  4. $ _{14}Si^{28}(d, n) _{15}P^{29}$


Correct Option: A

A proton and an alpha particle having same momentum enter a magnetic field at right angles to it. If $r _1$ and $r _2$ be their radii respectively then value of $r _1 /r _2$ is : 

  1. $1$

  2. $2$

  3. $1/2$

  4. $1/4$


Correct Option: B

$A5\times 10^{-4}\overset {o}{A}$ photon produces an electron-positron pair in the vicinity of a heavy nucleus. Rest energy of electron is 0.5 11 MeV. If they have the same kinetic energies, the energy of each particle is nearly

  1. 1.2 MeV

  2. 12 MeV

  3. 120 MeV

  4. 1200 MeV


Correct Option: B

If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should

  1. increase

  2. remain unchanged

  3. decrease

  4. first increase then decrease


Correct Option: A
Explanation:

Because thermal energy decreases, therefore mass should increase.

If 1mg of ${ U }^{ 235 }$ is completely annihilated, the energy liberated is

  1. $\quad 9\times { 10 }^{ 10 } J$

  2. $\quad 9\times { 10 }^{ 19} J$

  3. $\quad 9\times { 10 }^{ 18} J$

  4. $\quad 9\times { 10 }^{ 17} J$


Correct Option: A
Explanation:

$E={ mc }^{ 2 }={ 10 }^{ -6 }\times \left( 3\times { 10 }^{ 8 } \right) ^{ 2 }={ 10 }^{ -6 }\times 9\times { 10 }^{ 16 }=9\times { 10 }^{ 10 }J$