Class 12 Atoms CBSE Questions & Answers

Class 12 · Atoms

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

Questions & Answers

1
According to ‘plum pudding model’ atoms on the whole are electrically neutral because
  • A
    the positive charge of the atom is uniformly distributed throughout the volume of the electron and the negative charge of electrons balances positive parts
  • B
    the positive charge of the atom is uniformly distributed throughout the volume of the atom and the negatively charged electrons are embedded in it
    Correct
  • C
    positive charge is concentrated at one place and negative charge is elsewhere.
  • D
    the negative charge of the atom is uniformly distributed throughout the volume of the atom and the positively charged electrons are embedded in it
2
Each element is associated with
  • A
    with a characteristic spectrum of radiation
    Correct
  • B
    with a characteristic radiation of monochromatic light
  • C
    no light radiation or absorption
  • D
    with a characteristic absorption of monochromatic light
3
alpha particles used in Geiger-Marsden experiment were obtained from
  • A
    accelerating He ions
  • B
    electron accelerators
  • C
    \({}_{83}^{214}Bi\) Radioactive source
    Correct
  • D
    accelerating H ions
4
In Geiger-Marsden experiment very small deflection of the beam was expected because
  • A
    particles are collimated by lead screens
  • B
    positive charge and the negative electrons are distributed through the whole atom reducing electric field inside the atom
    Correct
  • C
    there are no electrical forces at work
  • D
    most particles pass through
5
Which of these statements correctly describe the atomic model according to classical electromagnetic theory ?
  • A
    electrons do not radiate electromagnetic waves
  • B
    the positive charge and negative electron cancel and no waves are radiated
  • C
    The waves emitted by electrons are discrete
  • D
    The electrons would spiral inwards and fall into the nucleus
    Correct
6
In Geiger-Marsden experiment prediction was that
  • A
    some particles would be expected at 45\(^\circ \)
  • B
    All the particles would go through the foil with hardly any deflection
    Correct
  • C
    All the particles would bounce from the foil at 180\(^\circ \)
  • D
    some particles would be expected at 75\(^\circ \)
7
The basic force acting on the alpha particles using coulombs law is
  • A
    \({{2Z{e^2}} \over {\pi { \in _0}{r^2}}}\)
  • B
    \({{2Z{e^2}} \over {4\pi { \in _0}{r^2}}}\)
    Correct
  • C
    \({{Z{e^2}} \over {4\pi { \in _0}{r^2}}}\)
  • D
    \({{2Z{e^2}} \over {4\pi {r^2}}}\)
8
In Geiger-Marsden experiment, at the point of closest approach
  • A
    the kinetic energy is not zero and the electrical potential is less than the initial kinetic energy supplied
  • B
    the kinetic energy is not zero and the electrical potential is greater than the initial kinetic energy supplied
  • C
    the kinetic energy is not zero and the electrical potential equals the initial kinetic energy supplied
  • D
    the kinetic energy is zero and the electrical potential equals the initial kinetic energy supplied
    Correct
9
In Geiger-Marsden experiment, actual results was
  • A
    Number of particles at angle \(\phi \) was zero at \(\phi \) =180\(^\circ \)
  • B
    Number of particles at angle \(\phi \) was zero at \(\phi \) =80\(^\circ \)
  • C
    Number of particles at angle \(\phi \) was zero at \(\phi \) =70\(^\circ \)
  • D
    Number of particles at angle \(\phi \) was non zero at all angles including at 180\(^\circ \)
    Correct
10
The model that best explains the results of Geiger-Marsden experiment is
  • A
    Bohr model
  • B
    Thomson model
  • C
    None of the above
  • D
    Rutherford model
    Correct
11
spectrum is
  • A
    The splitting into the component colors or wavelengths of light when passed through a lens.
  • B
    the splitting into the component colors or wavelengths of monochromatic light when passed through a prism or a diffraction grating
  • C
    The splitting into the component colors of white light when passed through a prism or a diffraction grating
  • D
    The splitting into the component colors or wavelengths of light when passed through a prism or a diffraction grating
    Correct
12
Continuous spectrum is produced by
  • A
    incandescent lamp
    Correct
  • B
    Hydrogen atoms in magnetic field
  • C
    lasers
  • D
    Hydrogen atoms in electrical field
13
Emission line spectrum of atoms contains
  • A
    Only a few colors in the form of isolated sharp parallel lines generally produced by heated gases
    Correct
  • B
    All colors of visible light without sharp boundaries
  • C
    All colors in the form of isolated sharp parallel lines generally produced by heated resistances
  • D
    Only a few colors in the form of isolated sharp parallel lines generally produced by chilled gases
14
Absorption line spectrum is obtained
  • A
    If we pass off-white (discrete-spectrum) light through a cool gas
  • B
    If we pass off-white (discrete-spectrum) light through a hot gas
  • C
    If we pass white (continuous-spectrum) light through a cool gas
    Correct
  • D
    If we pass white (continuous-spectrum) light through a hot gas
15
To produce an emission spectrum of hydrogen
  • A
    It needs to be in glowing gaseous form
    Correct
  • B
    It needs to be cold and white light shining through
  • C
    It needs to be cool liquid form
  • D
    It needs to be hot and white light shining through