Tag: nuclei

Quizzes (7) Questions (160)

Questions Related to nuclei

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Positronium is converted into

  1. 2 Photons each of energy 0.51MeV

  2. 1 Photon of energy 1.02 MeV

  3. 2 Photons each of energy 1.02MeV

  4. 1 Photon of energy 0.51MeV
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rest mass energy of a positron (as well as electron) is $0.51$ MeV.

Total rest mass energy of positron and electron is $2(0.51) = 1.02$ MeV
Thus a positron and an electron annihilate to produce two photons each of energy $0.51$ MeV. This phenomenon is known as positron-electron annihilation process.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

In pair annihilation, two  $\gamma $ -ray photons are produced due to

  1. Law of conservation of energy

  2. Law of conservation of mass

  3. Law of conservation of momentum

  4. Law of conservation of angular momentum
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When a particle encounters its antiparticle, they annihilate with the transformation of their mass energies into two gamma rays obeying law of conservation of mass.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Which one of the following cannot be used as a moderator in a nuclear reactor?

  1. Water

  2. Heavy water

  3. Molten sodium

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

Commonly used moderators in nuclear reactors include water, heavy water (D2O), and graphite, which slow down fast neutrons effectively. Molten sodium is used as a coolant to transfer heat from the reactor core, not as a moderator.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Which row describes the nature of $\alpha$- particles and of $\gamma$- rays

  1. $\alpha$- particles : helium nuclei ; $\gamma$ rays - electromagnetic radiation
  2. $\alpha$- particles : helium nuclei ; $\gamma$ rays - electrons
  3. $\alpha$- particles : protons; $\gamma$ rays - electromagnetic radiation
  4. $\alpha$- particles : protons; $\gamma$ rays - electrons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Characteristics of $\alpha$ particle
  mass= $4$ unit
  charge = $+2$ unit
The mass of Helium nuclei is $4$ unit and charge is $+2$ unit. So, it is equivalent to $\alpha $ particle .

$\gamma $- rays  is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei.
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

A scientist carries out an experiment using a sealed source which emits $\beta$ -particles. The range of the $\beta$- particles in the air is about $30cm$.
Which precaution is the most effective to protect the scientist from the radiation?

  1. handling the source with long tongs

  2. keeping the temperature of the source low

  3. opening all windows in the laboratory

  4. washing his hands before leaving the laboratory
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Handling the source with long tongs will prevent him from the exposure of $\beta$- particles. Since the range of $\beta$-particle is only $30cm$ so, long tongs can easily be a safer and effective precaution.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

One electron volt is equal to .......................

  1. $\displaystyle 1.6\times 10^{-19}$ Joule
  2. $\displaystyle 16\times 10^{-19}$ Joule
  3. $\displaystyle 1.6\times 10^{-10}$ Joule
  4. $\displaystyle 1.6\times 10^{-9}$ Joule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One electron volt is the energy gained by an electron accelerated through a potential difference of 1 volt, which is 1.6 * 10^-19 Joules.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

How much energy is released when a $ _{8}{O}^{16}$ nucleus is completely converted into energy?

The binding energy per nucleon of $ _{8}{O}^{16}$ is $7.97  MeV$ and ${m} _{p} = 1.0078  u$ and ${m} _{n} = 1.0087  u$

  1. $14899.438 MeV$
  2. $148.99 MeV$
  3. $4489.73 MeV$
  4. $448.973 MeV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Binding Energy $=E=\triangle mc^2$
$\triangle m=$ mass of nucleus $-$ (mass of proton + neutron)
Multiplying both sides by $c^2$
$\triangle mc^2=$ (mass of nucleus)$c^2 -$ (mass of proton + neutron)$c^2$
$=7.97\times 16-8(1.0078+1.0087)931 \\ E=127.52-15018.892 \\ E=-14899.438MeV$