Physics

Nuclear and Atomic Physics

571 Questions

Nuclear and atomic physics explores the components and properties of the nucleus, including isotopes, radioactive decay, and fundamental forces. These concepts are essential for various competitive exams requiring a strong foundation in physics. The provided questions cover structural properties, mass, energy equivalence, and particle interactions.

Nucleus propertiesIsotopes and mass numberAlpha particle scatteringNuclear forcesMass energy equivalenceBeta particle emission

Nuclear and Atomic Physics Questions

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

The nucleus of mass  $M +  \Delta m$  is at rest and decays into two daughter nuclei of equal mass  $\dfrac {  M  } { 2 }$  each. Speed of light is  $ c.$ The speed of daughter nuclei is

  1. $c \dfrac { \Delta m } { M + \Delta m }$
  2. $c \sqrt { \dfrac { 2 \Delta m } { M } }$
  3. $c \sqrt { \dfrac { \Delta m } { M } }$
  4. $c \sqrt { \dfrac { \Delta m } { M + \Delta m } }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Energy released Q = delta_m * c^2. This energy is shared as kinetic energy between the two daughter nuclei. K1 + K2 = Q. Since masses are equal, velocities are equal. 2 * (1/2 * (M/2) * v^2) = delta_m * c^2. (M/2) * v^2 = delta_m * c^2. v^2 = (2 * delta_m / M) * c^2. v = c * sqrt(2 * delta_m / M).

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

The particle $X$ in the following nuclear reaction is  $ _{7}^{13}\textrm{N}$ $\longrightarrow $ $ _{6}^{13}\textrm{C}+$  $ _{1}^{0}\textrm{e}$ + $X$

  1. $P$
  2. $v$
  3. $e^{-}$
  4. $\alpha$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The given reaction :      $^{13} _7N\rightarrow ^{13} _6C + ^0 _1e + ^A _Z X$

Conservation of mass number :      $13 = 13 + 0 +A$              $\implies A=0$
Conservation of atomic number :      $7 = 6 + 1 +Z$              $\implies Z=0$
Thus, the particle $X$ is neutrino i.e.  $\nu$

Multiple choice physics nuclei beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

Which word equation represents $\beta^+$ decay?

  1. Proton $\rightarrow$ neutron $+$ electron $+$ electron antineutrino
  2. Proton $\rightarrow$ neutron $+$ electron $+$ electron neutrino
  3. Proton $\rightarrow$ neutron $+$ positron $+$ electron antineutrino
  4. Proton $\rightarrow$ neutron $+$ positron $+$ electron neutrino
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 Positive beta decay $(β+\ \ \text{decay})$ also called the  positron emission. In this decay  a proton in the parent nucleus decays into a neutron that remains in the daughter nucleus, and the nucleus emits a neutrino and a positron, which is a positive particle like an ordinary electron in mass but of opposite charge. Thus, positive beta decay produces a daughter nucleus, the atomic number of which is one less than its parent and the mass number of which is the same.

The equation can be written as :

$p \rightarrow n+ e^+ + v _e$

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

In $\beta^-$ decay, a

  1. neutron converts into a proton emitting antineutrino.

  2. neutron converts into a proton emitting neutrino.

  3. proton converts into a neutron emitting antineutrino.

  4. proton converts into a neutron emitting neutrino.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reaction of beta decay is shown as :

$n \rightarrow p + e^- + \bar{\nu} _e$               (antineutrino)

So, in a $\beta-$ decay, a neutron converts into a proton emitting antineutrino.

option (A) is correct.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

In which of the following processes, the number of protons in the nucleus increase?

  1. $\alpha-decay$
  2. $\beta^--decay$
  3. $\beta^+-decay$

  4. k-capture
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

${ \beta  }^{ - }\quad decay$ :
Example: $ _{ 6 }^{ 14 }{ C }\longrightarrow _{ 7 }^{ 14 }{ N }+{ e }^{ - }+\bar { { v } _{ e } }$
Atomic number increases by 1 unit, which implies increase in proton.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

Masses of two isobars $ _{29}Cu^{64}$ and $ _{30}Zn^{64}$ are $63.9298\ u$ and $63.9292\ u$, respectively. It can be conclude from these data that

  1. Both the isobars are stable
  2. $Zn^{64}$ is radioactive, decaying to $Cu^{64}$ through $\beta-decay$
  3. $Cu^{64}$ is radioactive, decaying to $Zn^{64}$ through $\gamma-decay$
  4. $Cu^{64}$ is radioactive, decaying to $Zn^{64}$ through $\beta-decay$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Same no. of nucleons for $Cu^{64}$ and $Zn^{64}$
However, $M _{Cu}> M _{Zn}$
which indicates that the mass defect/ nuclear binding energy per nucleon is lesser of $Cu$, hence it will have a tendency to get to more stable form by $\beta $ decay.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

Neutron decay in free space is given as follows
$ _{ 0 }{ n }^{ 1 }\longrightarrow _{ 1 }{ H }^{ 1 }+ _{ 1 }{ e }^{ 0 }+$[  ]
Then the parenthesis [  ] represents a

  1. neutrino

  2. photon

  3. antineutrino

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

Since the charge is already conserved in the decay process, proton cannot be ejected.

To conserve the spin angular momentum of the initial neutron particle, an antineutrino (chargeless) is ejected.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

The number of neutrons in the element L in the following nuclear changes is 
$^{238} _{92}M\, \rightarrow\, ^x _y\, N\, +\, ^4 _2\, He$
$^X _YN\, \rightarrow\, ^A _BL\, +\, 2\beta^+$

  1. $146$
  2. $144$
  3. $140$
  4. $142$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$ _{ 92 }^{ 238 }{ M }\rightarrow _{ y }^{ x }{ N }+ _{ 2 }^{ 4 }{ He }$
$y=92-2=90 \\ x=238-4=234$
$ _{ 90 }^{ 234 }{ N }\rightarrow _{ B }^{ A }L+2 _{ +1 }^{ o }{ \beta  }\\ B=90-2=88\\ A=234$
no. of neutrons $=234-88 \\ =146$
So, $(A)$ is correct option.
Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

$^{11} _{6}C\, \rightarrow\,  ^{11} _{5}B$ decay produces -

  1. Positron
  2. $\beta$-particle
  3. $\alpha $-particle

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

The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of $+1e$, a spin of $\cfrac{1}{2}$ and has the same mass as an electron.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

Which of the following statement is correct?

  1. The rest mass of a stable nucleus is less than the sum of the rest masses of ts separated nucleons.

  2. The rest mass of a stable nucleus is greater than the sum of the rest masses of its separated nucleons

  3. In nuclear fission, energy is released by fusion two nuclei of medium mass (approximately 100 amu).

  4. In nuclear fission, energy is released by fragmentation of a very low nucleus.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stable nucleus has mass deficit: binding energy means M_nucleus < Σ(m_nucleons). This mass defect equals binding energy/c². Option B is wrong. Option C mentions fusion, not fission. Option D has 'very low nucleus' which is garbled; should say 'very heavy nucleus'.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

Find out the missing particle in the following nuclear reaction?
$^2 _1H+^{63} _{29}Cu \rightarrow ^{64} _{30}Zn+(?)$

  1. Proton

  2. Neutron

  3. Electron

  4. Positron

  5. Deuteron
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The given reaction :    $^2 _1 H$  $+$  $^{63} _{29} Cu  \rightarrow      ^{64} _{30} Zn  $  $+$  $^A _Z X$

In a nuclear reaction, mass number and the atomic number are conserved.
$\therefore$    $2+ 63  = 64 + A$   $\implies A = 1$
Also,  $1 + 29  = 30+Z$    $\implies Z = 0$
Thus, the missing particle is $^1 _0 n$  i.e  neutron.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

Compared to the parent nucleus, the daughter nucleus of a $\beta$ decay has:

  1. the same mass number but a smaller atomic number

  2. the same mass number but a greater atomic number

  3. a greater mass number but the same atomic number

  4. a smaller mass number but the same atomic number

  5. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When beta decay occurs, the atomic number of nucleus will increase by one unit and mass number will remain same. Thus, here the after beta decay the daughter nucleus has same mass number as product nuclei and one unit atomic number will increase than parent nuclei.    

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

When carbon $-14$ undergoes beta (electron) decay, it transmutes into what?

  1. $Carbon-13$
  2. $Carbon-12$
  3. $Nitrogen-13$
  4. $Nitrogen-12$
  5. $Nitrogen-14$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation
Beta decay of Carbon-14 : $^{14} _{6}   $ $ \rightarrow$  $^{A} _ZX $ $+$  $^{0} _{-1} e$

Conservation of mass number :  $14 = A+ 0$    $\implies A = 14$
Conservation of atomic number :  $6 = Z-1$    $\implies Z =7$
Thus the daughter nucleus is: $^{14} _{7} N$  or  $Nitrogen- 14$.
Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

In $\beta$ decay.

  1. Atomic number decreased by one

  2. Mass number decreases by one

  3. Proton number remains the same

  4. Neutron number decreases by one
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Beta decay of $ _Z^A X$ :    $ _Z^A X \rightarrow   _{Z+1}^A Y$ $+$ $  ^o _{-1}e$

Number of protons in X: $p _x = Z $
Number of neutrons in X: $n _x = A-Z$

Number of protons in Y: $ p _y= Z+1 $
Number of neutrons in X: $ n _y= A-(Z+1) =  A-Z - 1 $

$\implies$  $n _y = n _x -1$
Thus neutron number decreases by one in beta decay.

Multiple choice physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

When an atom undergoes $\beta$-decay, its atomic number

  1. Does not change
  2. Increases by $1$
  3. Decreases by $1$
  4. Increases by $2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
When an atom undergoes $\beta$-decay the atomic number increases by 1.

When an atom undergoes $\beta$-decay, one of the neutrons breaks into one proton and one electron. The resultant electron is then ejected out of the nucleus and this is called as the $\beta$ particle. While the resultant proton stays inside the nucleus which results in increase of atomic number by 1, whereas the atomic mass remains invariant.

Hence the correct answer is option B.