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
What percentage of the mass of an atom is concentrated in the nucleus?
  • A
    50.9\(\% \)
  • B
    66.9\(\% \)
  • C
    79.9\(\% \)
  • D
    99.9\(\% \)
    Correct
2
in what units is mass measured on the atomic scale?
  • A
    milligram
  • B
    Kilogram
  • C
    atomic mass units (u)
    Correct
  • D
    gram
3
Atomic mass unit (u), defined as
  • A
    1/\({\rm{1}}{{\rm{2}}^{{\rm{th}}}}\) of the mass of the carbon (\(^{{\rm{12}}}{\rm{C}}\)) atom
  • B
    1/\({\rm{1}}{{\rm{4}}^{{\rm{th}}}}\) of the mass of the carbon (\(^{{\rm{12}}}{\rm{C}}\)) atom
  • C
    1/\({\rm{1}}{0^{{\rm{th}}}}\) of the mass of the carbon (\(^{{\rm{12}}}{\rm{C}}\)) atom
  • D
    1/\({\rm{1}}{{\rm{2}}^{{\rm{th}}}}\) of the mass of the carbon (\(^{{\rm{12}}}{\rm{C}}\)) atom.
    Correct
4
A free neutron decays into
  • A
    a proton, a positron and a neutrino
  • B
    a proton, an electron and a neutrino
  • C
    a proton, a positron and a antineutrino
  • D
    a proton, an electron and an antineutrino
    Correct
5
Relation between atomic number (Z), neutron number (N) and mass number (A) is
  • A
    Z = A + 2N
  • B
    A= Z - N
  • C
    Z = A + N
  • D
    A = Z + N
    Correct
6
Nuclear species or nuclides are shown by the notation
  • A
    \({}_A^NX\)where X is the chemical symbol of the species
  • B
    \({}_N^AX\)where X is the chemical symbol of the species
  • C
    \((_Z^N)X\) where X is the chemical symbol of the species
  • D
    \({}_Z^AX\)where X is the chemical symbol of the species
    Correct
7
\({}_{79}^{197}Au\) Contains
  • A
    79 protons and 197 neutrons
  • B
    197 protons and 118 neutrons
  • C
    79 protons and 118 neutrons
    Correct
  • D
    79 neutrons and 118 protons
8
The nuclei of isotopes of a given element contain the same number of
  • A
    neutrons
  • B
    neutrinos
  • C
    positrons
  • D
    protons
    Correct
9
The nuclei of isotopes of a given element differ from each other in their number of
  • A
    protons
  • B
    neutrons
    Correct
  • C
    None of the above
  • D
    electrons
10
All nuclides with same mass number A are called
  • A
    isoclines
  • B
    isotones
  • C
    isobars
    Correct
  • D
    isotopes
11
Nuclides with same neutron number N but different atomic numbers Z are called
  • A
    isoclines
  • B
    isobars
  • C
    isotones
    Correct
  • D
    isotopes
12
a nucleus of mass number A has a radius R such that
  • A
    \(R = {R_0}{A^{{4 \over 3}}}\)
  • B
    \(R = {R_0}{A^{{1 \over 3}}}\)
    Correct
  • C
    \(R = {R_0}{A^{{5 \over 3}}}\)
  • D
    \(R = {R_0}{A^{{2 \over 3}}}\)
13
Nuclear mass M is found to be
  • A
    always equal to the total mass of its individual neutrons
  • B
    always equal to the total mass of its individual protons and neutrons
  • C
    always greater than total mass of its individual protons and neutrons
  • D
    always less than total mass of its individual protons and neutrons
    Correct
14
The difference in mass of a nucleus and its constituents is called
  • A
    rest mass
  • B
    mass number
  • C
    mass defect
    Correct
  • D
    lost mass
15
correct expression for mass defect \(\Delta \)m is
  • A
    \(Z{m_p} - \left( {A - Z} \right){m_n} + M\)
  • B
    \(Z{m_p} - \left( {A - Z} \right){m_n} - M\)
  • C
    \(Z{m_p} + \left( {A - Z} \right){m_n} + M\)
  • D
    \(Z{m_p} + \left( {A - Z} \right){m_n} - M\)
    Correct