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Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

$1$ $a.m.u$ is equivalent to 

  1. $931$ $MeV$

  2. $139$ $MeV$

  3. $93$ $MeV$

  4. $39$ $MeV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$m=1\ a.m.u.=1.66\times10^{-27}kg$

Its energy equivalent, using $E=mc^2$ is $E=1.49\times10^{-10}\ J$.
or $E=1.49\times10^{-10}/1.6\times10^{-13}\ MeV=931\ MeV$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

The binding energy per nucleon of deuteron $ \left( \frac { 2 }{ 1 }  H \right)  $ and helium nucleus $ \left( \frac { 4 }{ 2 } He \right)  $ is.1.1 meV and 7 meV respectively. If two deuteron nuclei react to from s single helium nucleus, then the energy released is:

  1. 13.9 MeV

  2. 26.9 MeV

  3. 23.6 MeV

  4. 19.2 MeV
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total binding energy of two deuterons = 2 × 2.2 = 4.4 MeV. Total binding energy of helium = 4 × 7 = 28 MeV. Energy released = 28 - 4.4 = 23.6 MeV. Note: This is another duplicate with 'meV' typo (should be MeV).

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

The binding energy expressed in $MeV$ is given for the following nuclear reactions :
$ _2He^3+\ _0n^1\rightarrow\ _2He^4+20\ MeV$
$ _2He^4+\ _0n^1 \rightarrow\ _2He^5 -0.9\ MeV$
Which of the following conclusions are correct ?

  1. $ _2He^4$ is less stable than both $ _2He^3$ and $ _2He^5$

  2. $ _2He^4$ is less stable than $ _2He^3$ but more stable than $$ _2He^5$

  3. $ _2He^4$ is less stable than $ _2He^5$ but more stable than $$ _2He^3$

  4. $ _2 He^4$ is more stable than both $ _2He^3$ and $ _2He^5$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A positive energy release (Q > 0) indicates a stable product, while a negative energy release (Q < 0) indicates an unstable product. Since the first reaction releases 20 MeV, He-4 is more stable than He-3. Since the second reaction requires 0.9 MeV, He-5 is less stable than He-4.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

An electron and a positron are moving side by side in the positive $x-$direction at $1.5\times 10^8\ m/s$. When they annihilate each other, two photons are produced that move along the $x-$axis, then : 

  1. both move in positive $x-$direction

  2. both move in positive direction along $x-$axis

  3. both may move in same direction

  4. both $(a)$ and $(c)$ are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the reaction, we need to identify what M represents. Based on nuclear reaction notation and the fact that it appears after the product nucleus, M is a neutron that is emitted in the reaction. The reaction shows helium-4 bombarding target X, producing an excited nucleus that emits gamma rays and a neutron.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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. $^{m-4} _{n-2}D$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alpha decay involves the emission of a helium nucleus, which has a mass number of 4 and an atomic number of 2. Therefore, the daughter nucleus must have a mass number reduced by 4 and an atomic number reduced by 2.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The reaction shows a heavy nucleus being bombarded and breaking down into a lighter nucleus with the emission of multiple protons and neutrons. This process of splitting or breaking down is characteristic of nuclear separation or fission-like processes.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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
Reveal answer Fill a bubble to check yourself
A Correct answer
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 } } $