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
What is the shortest wavelength present in the Paschen series of spectral lines?
  • A
    800 nm
  • B
    860 nm
  • C
    840 nm
  • D
    820 nm
    Correct
2
Suppose you are given a chance to repeat the alpha-particle scattering experiment using a thin sheet of solid hydrogen in place of the gold foil. (Hydrogen is a solid at temperatures below 14 K.) What results do you expect?
  • A
    there would be scattering at 90\(^\circ \)
  • B
    there would be no scattering
  • C
    there would be no large-angle scattering
    Correct
  • D
    there would be scattering at all angles
3
In comparison to atomic size in Rutherford’s model, the size of the atom in Thomson’s model is
  • A
    no different
    Correct
  • B
    much greater
  • C
    much less
  • D
    slightly less
4
In the ground state of which model electrons are in stable equilibrium with zero net force?
  • A
    Rutherford’s model
  • B
    No model
  • C
    Thomson’s model
    Correct
  • D
    Bohr model
5
According to which model a classical atom is doomed to collapse?
  • A
    No model
  • B
    Rutherford’s model
    Correct
  • C
    Bohr model
  • D
    Thomson’s model
6
In which of the models An atom has a nearly continuous mass distribution?
  • A
    Bohr model
  • B
    Rutherford’s model
  • C
    No model
  • D
    Thomson’s model
    Correct
7
In which of the models An atom has a highly non-uniform mass distribution?
  • A
    Thomson’s model
  • B
    Rutherford’s model
    Correct
  • C
    No model
  • D
    Bohr model
8
In which of the models, the positively charged part of the atom possesses most of the mass?
  • A
    Rutherford’s model only
  • B
    Bohr model only
  • C
    Thomson’s model only
  • D
    Thomson’s model and Rutherford’s model
    Correct
9
A difference of 2.3 eV separates two energy levels in an atom. What is the frequency of radiation emitted when the atom make a transition from the upper level to the lower level?
  • A
    5.1 \( \times {\rm{ 1}}{0^{{\rm{14}}}}\) Hz
  • B
    5.6 \( \times {\rm{ 1}}{0^{{\rm{14}}}}\) Hz
    Correct
  • C
    6.6 \( \times {\rm{ 1}}{0^{{\rm{14}}}}\) Hz
  • D
    6.1 \( \times {\rm{ 1}}{0^{{\rm{14}}}}\) Hz
10
The ground state energy of hydrogen atom is –13.6 eV. What are the kinetic and potential energies of the electron in this state?
  • A
    13.6 eV, –27.2 eV
    Correct
  • B
    14.6 eV, –29.2 eV
  • C
    14.6 eV, –27.2 eV
  • D
    13.1 eV, –29.2 eV
11
A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. Determine the wavelength and frequency of photon
  • A
    \({\rm{9}}.{\rm{7 }} \times {\rm{ 1}}{0^{-{\rm{ 8}}}}{\rm{m}},{\rm{ 3}}.{\rm{1 }} \times {\rm{ 1}}{0^{{\rm{15}}}}\)Hz.
    Correct
  • B
    \({\rm{9}}.{\rm{7 }} \times {\rm{ 1}}{0^{-{\rm{ 8}}}}{\rm{m}},{\rm{ 4}}.{\rm{1 }} \times {\rm{ 1}}{0^{{\rm{15}}}}\)Hz.
  • C
    \({\rm{1}}0.{\rm{7 }} \times {\rm{ 1}}{0^{-{\rm{ 8}}}}{\rm{m}},{\rm{ 3}}.{\rm{1 }} \times {\rm{ 1}}{0^{{\rm{15}}}}\) Hz.
  • D
    \({\rm{8}}.{\rm{7 }} \times {\rm{ 1}}{0^{-{\rm{ 8}}}}{\rm{m}},{\rm{ 3}}.{\rm{1 }} \times {\rm{ 1}}{0^{{\rm{15}}}}\)Hz.
12
Using the Bohr’s model calculate the speed of the electron in a hydrogen atom in the n = 1, 2, and 3 levels.
  • A
    2.38 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 1.39 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 7.37 \( \times {\rm{ 1}}{0^{\rm{5}}}\) m/s
  • B
    2.08 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 1.00 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 7.20 \( \times {\rm{ 1}}{0^{\rm{5}}}\) m/s
  • C
    2.18 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 1.09 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 7.27 \( \times {\rm{ 1}}{0^{\rm{5}}}\) m/s
    Correct
  • D
    2.28 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 1.29 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s; 7.22 \( \times {\rm{ 1}}{0^{\rm{5}}}\) m/s
13
Using the Bohr’s model Calculate the orbital period of the electron in a hydrogen atom in the n = 1, 2, and 3 levels.
  • A
    1.72 \( \times {\rm{ 1}}{0^{-{\rm{16}}}}\) s; 1.22 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s; 4.11 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s
  • B
    1.62 \( \times {\rm{ 1}}{0^{-{\rm{16}}}}\) s; 1.22 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s; 4.11 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s
  • C
    1.42 \( \times {\rm{ 1}}{0^{-{\rm{16}}}}\) s; 1.22 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s; 4.11 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s
  • D
    1.52 \( \times {\rm{ 1}}{0^{-{\rm{16}}}}\) s; 1.22 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s; 4.11 \( \times {\rm{ 1}}{0^{-{\rm{15}}}}\) s.
    Correct
14
The radius of the innermost electron orbit of a hydrogen atom is 5.3×10–11 m. What are the radii of the n = 2 and n =3 orbits?
  • A
    2.22\( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m; 4.27 \( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m
  • B
    2.42\( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m; 4.47 \( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m
  • C
    2.32\( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m; 4.37 \( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m
  • D
    2.12\( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m; 4.77 \( \times {\rm{ 1}}{0^{-{\rm{1}}0}}\) m
    Correct
15
A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?
  • A
    Lyman series: 143 nm and 122 nm; Balmer series: 646 nm.
  • B
    Lyman series: 103 nm and 122 nm; Balmer series: 656 nm.
    Correct
  • C
    Lyman series: 133 nm and 123 nm; Balmer series: 656 nm.
  • D
    Lyman series: 153 nm and 125 nm; Balmer series: 556 nm.