Class 12 Nuclei CBSE Questions & Answers

Class 12 · Nuclei

This is Physics Class 12 Nuclei CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
binding energy of the nucleus Eb is related to mass defect Δm by
  • A
    \({{\rm{E}}_{\rm{b}}} = {\rm{ }}\Delta {\rm{m }}{{\rm{c}}^{\rm{2}}}\)
    Correct
  • B
    \({{\rm{E}}_{\rm{b}}} = {\rm{ }}\Delta {\rm{m }}{{\rm{c}}^{\rm{4}}}\)
  • C
    \({{\rm{E}}_{\rm{b}}} = {\rm{ 2}}\Delta {\rm{m }}{{\rm{c}}^{\rm{2}}}\)
  • D
    \({{\rm{E}}_{\rm{b}}} = {\rm{ }}\Delta {\rm{m }}{{\rm{c}}^{\rm{3}}}\)
2
In the mass number range A = 30 to 170, the binding energy per nucleon is
  • A
    nearly constant
    Correct
  • B
    increases linearly with A
  • C
    decreases linearly with A
  • D
    decreases with increasing A
3
Energies associated with nuclear processes are
  • A
    about a 100 times larger than chemical process
  • B
    about a thousand times larger than chemical process
  • C
    about a ten times larger than chemical process
  • D
    about a million times larger than chemical process
    Correct
4
The disintegration energy is
  • A
    the difference between the initial mass and the total mass of the decay products
  • B
    None of the above
  • C
    the difference between the initial energy and the total energy of the decay products
  • D
    the difference between the initial mass energy and the total mass energy of the decay products
    Correct
5
Radioactivity is the phenomenon in which
  • A
    nuclei of a given species transform by giving out \(\beta \) rays;
  • B
    nuclei of a given species transform by giving out \(\alpha \) rays;
  • C
    nuclei of a given species transform by giving \(\gamma \) rays;
  • D
    nuclei of a given species transform by giving out \(\alpha {\rm{ or }}\beta {\rm{ or }}\gamma \) rays;
    Correct
6
\(\alpha \) -rays are
  • A
    helium nuclei
    Correct
  • B
    hydrogen nuclei
  • C
    heavy nuclei
  • D
    lithium nuclei
7
\(\beta \) -rays and \(\gamma \) -rays are respectively
  • A
    protons and neutrons of wavelengths shorter than X-rays
  • B
    protons and electromagnetic radiation of wavelengths shorter than X-rays
  • C
    electrons and electromagnetic radiation of wavelengths shorter than X-rays
    Correct
  • D
    neutrons and electromagnetic radiation of wavelengths shorter than X-rays
8
Law of radioactive decay is
  • A
    \(N\left( t \right) = N(0){e^{ - t}}\)
  • B
    \(N\left( t \right) = N(0){e^{ - \lambda t}}\)
    Correct
  • C
    \(N\left( t \right) = N(0){e^2}{t^2}\)
  • D
    \(N\left( t \right) = N(0){e^4}{t^2}\)
9
The half-life \({{\rm{T}}_{{\rm{1}}/{\rm{2}}}}\)of a radionuclide is
  • A
    the time in which N has been increased to double its initial value
  • B
    the time in which N has been reduced to one-half of its initial value
    Correct
  • C
    the time in which N has been reduced to one-half of a standard fixed amount
  • D
    none of the above
10
The mean life t of a radionuclide is
  • A
    the time at which N has been reduced to \({{\rm{e}}^{-{\rm{1}}}}\)of its initial value
    Correct
  • B
    the most probable time a radionuclide continues to emit
  • C
    the time at which N has been reduced to one-half of its initial value
  • D
    the average time a radionuclide continues to emit
11
The particles or radiation emitted in the nuclear reaction \(_{\rm{Z}}{{\rm{X}}^{\rm{A}}}{ \to _{{\rm{Z}} + {\rm{1}}}}{{\rm{Y}}^{\rm{A}}}{ \to _{{\rm{Z}} - {\rm{1}}}}{{\rm{R}}^{{\rm{A }} - {\rm{ 4}}}}{ \to _{{\rm{Z}} - {\rm{1}}}}{{\rm{R}}^{{\rm{A}} - {\rm{4}}}}\) will be respectively,
  • A
    \(\alpha ,{\rm{ }}\beta ,{\rm{ }}\gamma \)
  • B
    \(\beta ,{\rm{ }}\alpha ,{\rm{ }}\gamma \)
    Correct
  • C
    \(\beta ,{\rm{ }}\gamma ,{\rm{ }}\alpha \)
  • D
    \(\gamma ,{\rm{ }}\alpha ,{\rm{ }}\beta \)
12
Which rays are not deflected in electric and magnetic fields?
  • A
    \(\beta \) –rays
  • B
    \(\chi \) –rays
  • C
    \(\gamma \) –rays
    Correct
  • D
    none of these
13
The half life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after
  • A
    6400 years
  • B
    4800 years
  • C
    3200 years
    Correct
  • D
    2400 years
14
A radioactive element X with a half life of 2 hours decays giving a stable element Y. After a time of t hours ratio of X to Y atoms is 1:7, then the value of t is
  • A
    4
  • B
    14.0
    Correct
  • C
    Between 4 and 6
  • D
    6
15
An electric field can deflect
  • A
    Gamma rays
  • B
    Neutrons
  • C
    \(\alpha \) –particle
    Correct
  • D
    \(\chi \) rays