Tag: nuclear reactions

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Questions Related to nuclear reactions

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 } } $

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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

In option A, the mass number change is 243-242 = 1, but the reaction is (alpha, 2n). An alpha particle adds 4 to the mass and 2 to the atomic number, while 2 neutrons remove 2 from the mass. The net change should be +2 mass and +2 atomic number, making the product Cm-242 + He-4 - 2n = Bk-244, not Bk-243.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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. $1/4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The radius of a charged particle in a magnetic field is r = p / (qB). Since both particles have the same momentum p and enter the same field B, the ratio r1/r2 = q2/q1. A proton has charge 1 and an alpha particle has charge 2, so r1/r2 = 2/1 = 2.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

$A5\times 10^{-4}\overset {o}{A}$ 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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photon wavelength: λ = 5 × 10⁻⁴ Å = 5 × 10⁻¹⁴ m. Energy: E = hc/λ = (1240 eV·nm)/(5 × 10⁻⁵ nm) ≈ 24.8 MeV. Total rest energy of e⁻e⁺ pair: 2 × 0.511 = 1.022 MeV. Available kinetic energy: 24.8 - 1.022 ≈ 23.78 MeV. Each particle gets half: ≈ 11.89 MeV, approximately 12 MeV. Note: '0.5 11 MeV' appears to be typo for 0.511 MeV.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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

Because thermal energy decreases, therefore mass should increase.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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. $\quad 9\times { 10 }^{ 17} J$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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