Free PDF Download of CBSE Class 12 Physics Chapter 12 Atoms Assertion Reason Questions for Class 12 Physics. Class 12 Physics Assertion Reason Questions with Answers were Prepared Based on the Latest Exam Pattern. Students can solve NCERT Class 12 Physics Atoms to know their preparation level.
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Atoms Class 12 Assertion Reason Questions
The following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion (A) : The force of repulsion between atomic nucleus and a-particle varies with distance according to inverse square law.
Reason (R) : Rutherford did a-particle scattering experiment.
(b) Both A and R are true but R is not the correct explanation of A.
Assertion (A) : According to classical theory, the proposed path of an electron in Rutherford atom model will be circular.
Reason (R) : According to electromagnetic theory an accelerated particle continuously emits radiation.
(b) Both A and R are true but R is not the correct explanation of A.
Assertion (A) : Between any two given energy levels, the number of absorption transitions is always less than the number of emission transitions.
Reason (R) : Absorption transitions start from the lowest energy level only and may end at any higher energy level. But emission transitions may start from any higher energy level and end at any energy level below it.
(a) Both A and R are true and R is the correct explanation of A.
Assertion (A) : Electrons in the atom are held due to coulomb forces.
Reason (R) : The atom is stable only because the centripetal force due to Coulomb’s law is balanced by the centrifugal force.
(c) A is true but R is false.
Assertion (A) : Total energy of revolving electron in any stationary orbit is negative.
Reason (R) : Energy is a scalar quantity. It can have positive or negative value.
(b) Both A and R are true but R is not the correct explanation of A.
Assertion (A) : For the scattering of a-particles at large angles, only the nucleus of the atom is responsible.
Reason (R) : Nucleus is very heavy in comparison to electrons.
(a) Both A and R are true and R is the correct explanation of A.
Assertion (A) : Fraunhofer lines are observed in the spectrum of the sun.
Reason (R) : The different elements have different spectra.
(b) Both A and R are true but R is not the correct explanation of A.
Assertion : In Lyman series, the ratio of minimum and maximum wavelength is 3/4
Reason : Lyman series constitute spectral lines corresponding to transition from higher energy to ground state of hydrogen atom.
(b) Both A and R are true but R is not the correct explanation of A.
Assertion : Between any two given energy levels, the number of absorption transitions is always less than the number of emission transitions.
Reason : Absorption transitions start from the lowest energy level only and may end at any higher energy level. But emission transitions may start from any higher energy level and end at any energy level below it.
(a) Both A and R are true and R is the correct explanation of A.
Assertion : Electrons in the atom are held due to coulomb forces.
Reason : The atom is stable only because the centripetal force due to Coulomb’s law is balanced by the centrifugal force.
(c) A is true but R is false.
Assertion (A): The atomic spectra of different elements are unique and can be used for identification.
Reason (R): Each element has its own set of energy levels and transitions, resulting in distinct spectral lines.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The Rydberg formula can be used to calculate the wavelengths of spectral lines in hydrogen-like atoms.
Reason (R): The Rydberg formula is based on the energy levels of the electron in the hydrogen atom.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): In the Bohr model of the hydrogen atom, electrons revolve around the nucleus in circular orbits of fixed radii.
Reason (R): The angular momentum of the electron is quantized in the Bohr model, leading to the restriction of specific allowed orbits.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The Balmer series in the hydrogen spectrum consists of lines corresponding to electron transitions to the second energy level (n=2).
Reason (R): The Balmer series results from transitions of electrons from higher energy levels to the second energy level.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The de Broglie wavelength of an electron is inversely proportional to its momentum.
Reason (R): The de Broglie wavelength of a particle is given by λ = h / p, where h is Planck’s constant and p is the momentum of the particle.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The photoelectric effect can be explained by considering light as discrete packets of energy called photons.
Reason (R): Photons, with energy proportional to the frequency of light, transfer their energy to electrons, causing them to be emitted from a metal surface.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The energy levels in multi-electron atoms are more complex than those in hydrogen-like atoms.
Reason (R): The presence of multiple electrons in an atom leads to electron-electron repulsions and additional energy levels.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The ground state of an atom is the state of lowest energy, with all electrons in their lowest possible energy levels.
Reason (R): In the ground state, electrons occupy the lowest energy orbitals available.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The Heisenberg uncertainty principle states that it is impossible to simultaneously determine the exact position and momentum of an electron.
Reason (R): The act of measurement of position and momentum of an electron disturbs the electron’s state, making it impossible to know both properties with certainty.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Assertion (A): The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers.
Reason (R): The Pauli exclusion principle is a consequence of the wave nature of electrons and is essential for the stability of matter.
Answer: (a) Both A and R are true and R is the correct explanation of A.
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