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
Using the Bohr model, calculate the speed of the electron in a hydrogen atom in the n = 1, 2, and 3 levels.
  • A
    2.28 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 1.19 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 7.17 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
  • B
    2.38 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 1.29 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 7.22 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
  • C
    2.48 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 1.39 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 7.37 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
  • D
    2.18 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 1.09 \( \times {\rm{ 1}}{0^{\rm{6}}}\), 7.27 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
    Correct
2
Using the Bohr model, calculate the orbital period in each of the n = 1, 2, and 3 levels
  • A
    1.55 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 1.42 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 4.33 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s
  • B
    1.54 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 1.32 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 4.23 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s
  • C
    1.56 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 1.52 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 4.43 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s
  • D
    1.53 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 1.22 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s, 4.13 \( \times {\rm{ 1}}{0^{ - {\rm{16}}}}\) s
    Correct
3
The average lifetime of the first excited level of a hydrogen atom is 1.0 \( \times {\rm{ 1}}{0^{ - {\rm{8}}}}\) s. In the Bohr model, how many orbits does an electron in the n = 2 level complete before returning to the ground level?
  • A
    8.7 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
  • B
    9.2 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
  • C
    9.7 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
  • D
    8.2 \( \times {\rm{ 1}}{0^{\rm{6}}}\)
    Correct
4
In a set of experiments on a hypothetical one-electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground state (n = 1) as shown in the energy-level diagram in figure. You also observe that it takes 17.50 eV to ionize this atom. What is the energy of the atom in n = 1?
Question 4 figure 1
  • A
    17.50 eV
  • B
    -19.50 eV
  • C
    -18.50 eV
  • D
    -17.50 eV
    Correct
5
In a set of experiments on a hypothetical one-electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground state ( n = 1) as shown in the energy-level diagram in figure. You also observe that it takes 17.50 eV to ionize this atom. What is the energy of the atom in n = 2?
Question 5 figure 1
  • A
    -4.58 eV
  • B
    -4.48 eV
  • C
    -4.68 eV
  • D
    -4.38 eV
    Correct
6
In a set of experiments on a hypothetical one-electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground state ( n = 1) as shown in the energy-level diagram in figure. You also observe that it takes 17.50 eV to ionize this atom. What is the energy of the atom in n = 3?
Question 6 figure 1
  • A
    -1.95 eV
    Correct
  • B
    -2.15 eV
  • C
    -1.85 eV
  • D
    -2.05 eV
7
In a set of experiments on a hypothetical one-electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground state ( n = 1) as shown in the energy-level diagram in figure. You also observe that it takes 17.50 eV to ionize this atom. What is the energy of the atom in n = 4?
Question 7 figure 1
  • A
    -1.30 eV
  • B
    -1.40 eV
  • C
    -1.10 eV
    Correct
  • D
    -1.20 eV
8
In a set of experiments on a hypothetical one-electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground state ( n = 1) as shown in the energy-level diagram in figure. You also observe that it takes 17.50 eV to ionize this atom. What is the energy of the atom in n = 5?
Question 8 figure 1
  • A
    -0.81 eV
  • B
    -0.71 eV
    Correct
  • C
    -0.51 eV
  • D
    -0.61 eV
9
In a set of experiments on a hypothetical one-electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground state ( n = 1) as shown in the energy-level diagram in figure. You also observe that it takes 17.50 eV to ionize this atom. If an electron made a transition from the n = 4 to the n = 2 level, what wavelength of light would it emit?
Question 9 figure 1
  • A
    398 nm
  • B
    358 nm
  • C
    338 nm
  • D
    378 nm
    Correct
10
The ground state energy of hydrogen atom is –13.6 eV. Find the orbital radius and velocity of the electron in a hydrogen atom
  • A
    5.5 \( \times {\rm{ 1}}{0^{ - {\rm{11}}}}\) m, 2.4 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s
  • B
    5.4 \( \times {\rm{ 1}}{0^{ - {\rm{11}}}}\) m, 2.3 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s
  • C
    5.6 \( \times {\rm{ 1}}{0^{ - {\rm{11}}}}\) m, 2.5 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s
  • D
    5.3 \( \times {\rm{ 1}}{0^{ - {\rm{11}}}}\) m, 2.2 \( \times {\rm{ 1}}{0^{\rm{6}}}\) m/s
    Correct
11
An electron collides with a hydrogen atom in its ground state and excites it to a state of n = 3. How much energy was given to the hydrogen atom in this inelastic collision?
  • A
    12.1 eV
    Correct
  • B
    15.1 eV
  • C
    13.1 eV
  • D
    14.1 eV
12
Hydrogen atoms in states of high quantum number have been created in the laboratory observed in space. They are called Rydberg atoms. Find the quantum number of the Bohr orbit in a hydrogen atom whose radius is 0.0100 mm. What is the energy of a hydrogen atom in this state?
  • A
    455, -7.29 \( \times {\rm{ 1}}{0^{ - {\rm{5}}}}\) eV
  • B
    495, -7.49 \( \times {\rm{ 1}}{0^{ - {\rm{5}}}}\) eV
  • C
    435, -7.19 \( \times {\rm{ 1}}{0^{ - {\rm{5}}}}\) eV
    Correct
  • D
    475, -7.39 \( \times {\rm{ 1}}{0^{ - {\rm{5}}}}\) eV
13
Find the longest wavelength present in the Balmer series of hydrogen, corresponding to the H- line.
  • A
    666 nm
  • B
    676 nm
  • C
    656 nm
    Correct
  • D
    686 nm
14
Find the frequencies of revolution of electrons in n = 1 and n = 2 Bohr orbits
  • A
    6.68 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s, 0.863 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s
  • B
    6.58 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s, 0.823 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s
    Correct
  • C
    6.78 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s, 0.893 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s
  • D
    6.88 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s, 0.923 \( \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev/s
15
Which of these statements about Bohr model hypothesis is correct?
  • A
    electron in a stable orbit emit quanta of light
  • B
    velocity of electron is quantized
  • C
    angular momentum is not quantized
  • D
    electron in a stable orbit does not radiate electromagnetic waves
    Correct