Tag: atomic nuclei

Quizzes (8) Questions (121)

Questions Related to atomic nuclei

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

The relation between the volume $V$ and the mass $M$ of a nucleus is:

  1. $V\propto M^{3}$
  2. $V\propto M^{1/3}$
  3. $V\propto M$
  4. $V\propto 1/M$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since the density of nucleus is fixed.

$D=\cfrac { M }{ V } \ \Rightarrow M=DV\ M\propto V$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

A student wrote the relation for one unified atomic mass unit (u) as $1u=931.5MeV$. What is the correct relation?

  1. $1 u\times c=931.5 MeV$
  2. $1 u\times c^2=931.5 MeV$
  3. $\dfrac{1u}{c^2}=931.5 MeV$
  4. $(1u)^2\times c=931.5Me V$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$1u=931.5 MeV$
we know $1u=1.66\times 10^{-21}kv$
$931.5 MeV=931.5\times 10^6\times 1.6\times 10^{-19}J=1.49\times 10^{-10}$
$E=(1u)(c^2)=(1.66\times 10^{-27})(3\times 10^8)^2J=1.494\times 10^{-10}J$
so $(1u)(c)^2=931.5MeV$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

A nucleus of mass number $A$ originally at rest emits $\alpha$- particle with speed $v$. The recoil speed of daughter nucleus is:

  1. $\cfrac{4v}{A-4}$
  2. $\cfrac{4v}{A+4}$
  3. $\cfrac{v}{A-4}$
  4. $\cfrac{v}{A+4}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

By conservation of momentum, the momentum of the alpha particle (mass 4, speed v) must equal the momentum of the daughter nucleus (mass A-4, speed V). Thus, 4v = (A-4)V, so V = 4v / (A-4).

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

As the mass number increase, binding energy per nucleon,

  1. increases

  2. decreases

  3. remain same

  4. may increase or may decrease
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The binding energy per nucleon curve rises sharply for light nuclei, peaks around iron (mass number 56), and then gradually decreases for heavier nuclei.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Per nucleon energy of $ _ { 3 } L ^ { 7 }$ and $2 ^ { \mathrm { H } e ^ { 4 } }$  nucleus is 5. 60  MeV and 7.06 MeV then in$ _ { 3 } \mathrm { L } ^ { 7 } + _ { 1 } \mathrm { P } ^ { 1 } \rightarrow 2 _ { 2 } \mathrm { He } ^ { 4 }$ energy released is:

  1. $29.6 \mathrm { MeV }$
  2. $2.4MeV$
  3. $8.4 \mathrm { MeV }$
  4. $17.3 \mathrm { MeV }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Mass defect of an atom refers to 

  1. inaccurate measurement of mass of neutrons

  2. mass annihilated to produce energy to bind the nucleons

  3. packing fraction

  4. difference in the number of neutrons and protons in the nucleus
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$ Mc^{2} + (B.E) = (N _{mN} + Z _{mP})c^{2}$
where,
         $M _{c} =  $  total mass of nucleus.
         $N _{mN} =  $  total mass of neutrons
         $N _{mP}  =  $  total mass of protons

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

In a fission process, nucleus A divides into two nuclei B and C, their binding energies being $\mathbf { E } _ { \mathbf { a } ^ { * } }$   $E _ { b }$  and $E _ { c }$ respectively. Ihen

  1. $\mathbf { E } _ { \mathrm { b } } + \mathrm { E } _ { \mathrm { c } } = \mathrm { E } _ { \mathrm { a } }$
  2. $\mathrm { E } _ { \mathrm { b } } + \mathrm { E } _ { \mathrm { c } } > \mathrm { E } _ { \mathrm { a } }$
  3. $\mathrm { E } _ { \mathrm { b } } + \mathrm { E } _ { \mathrm { e } } < \mathrm { E } _ { \mathrm { a } }$
  4. $\mathrm { E } _ { \mathrm { b } } \mathrm { E } _ { \mathrm { c } } = \mathrm { E } _ { \mathrm { a } }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$\begin{array}{l} { E _{ b } }+{ E _{ c } }>{ E _{ a } } \ \, \because some\, \, energy\, \, is\, \, goen\, \, in\, \, breaking\, \, nuclie\, \, of\, \, A \ Hence, \ option\, \, A\, \, is\, \, correct\, \, answer. \end{array}$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

For uranium nucleus. Find relation between mass and volume 

  1. $m\propto v$
  2. $m\propto \sqrt{v}$
  3. $m\propto v^2$
  4. $m\propto \dfrac{1}{v}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nuclear density is constant, so mass m = density * volume. Therefore, m is directly proportional to volume (m proportional to v).

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

The phenomenon of pair production is :

  1. The production of an electron and a positron from $\gamma$ radiation

  2. Ejection of an electron from a metal surface when exposed to ultraviolet light

  3. Ejection of an electron from a nucleus

  4. Ionization of a neutral atom
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pair production :
Gamma rays of sufficient energy when passing near a nucleus disappear and materialize into pair of an electron and a positron.
To have pair production, minimum energy of $\gamma$ - ray radiation is 1.02MeV.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

In pair annihilation the least number of  $\gamma $- ray photons produced is :

  1. 2

  2. 3

  3. 4

  4. 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a pair annihilation, atleast two gamma rays must be produced. For example, when an electron encounters a positron, they annihilate to produce two gamma rays each having $0.511$ MeV energy.