Class 12 CBSE Physics Atoms Boards Questions
Here we provide Class 12 physics important notes,board questions and predicted questions with Answers for chapter Atoms. These important notes,board questions and predicted questions are based on CBSE board curriculum and correspond to the most recent Class 12 physics syllabus. By practising these Class 12 materials, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 12 Board examinations.
2017
Q1
A 12·5 eV electron beam is used to excite a gaseous hydrogen atom at room temperature. Determine the
wavelengths and the corresponding series of the lines emitted.
solutions
solutions
2018
Q2
(a) State Bohr’s postulate to define stable- orbits in hydrogen atom. How does de Broglie’s
hypothesis explain the stability of these orbits ?
(b) A hydrogen atom initially in the ground state absorbs a photon which excites it to the n = 4 level. Estimate the frequency of the photon.
solutions
(b) A hydrogen atom initially in the ground state absorbs a photon which excites it to the n = 4 level. Estimate the frequency of the photon.
solutions
2019
Q3
State bohr’s quantization condition of angular momentum calculate shortest wavelength of the bracket
series and state to which part of the electromagnetic spectrum does it belong.
solutions
solutions
2020
Q4
A hydrogen atom initially in its ground state absorb a photon and is in the excited state with
energy 12.5 eV. Calculate the longest wavelength of the radiation emitted and rectifier the series
to which it belongs [Take Rydberg’s constant = 1.1 x 107 m-1]
solutions
solutions
Q5
Which of the following statements is not correct according to Rutherford model ?
(A) Most of the space inside an atom is empty.
(B) The electrons revolve around the nucleus under the influence of coulomb force acting on them.
(C) Most part of the mass of the atom and its positive charge are concentrated at its centre.
(D) The stability of atom was established by the model.
solutions
(A) Most of the space inside an atom is empty.
(B) The electrons revolve around the nucleus under the influence of coulomb force acting on them.
(C) Most part of the mass of the atom and its positive charge are concentrated at its centre.
(D) The stability of atom was established by the model.
solutions
Q6
According to Bohr’s atomic model, the circumference of the electron orbit is always an ___________
multiple of de Broglie wavelength.
OR
In β;-decay, the parent and daughter nuclei have the same number of _____________ .
solutions
In β;-decay, the parent and daughter nuclei have the same number of _____________ .
solutions
Q7
Using Bohr’s atomic model, derive the expression for the radius of n th orbit of the revolving
electron in a hydrogen atom.
OR
(a) Write two main observations of photoelectric effect experiment which could only be explained by Einstein’s photoelectric equation.
(b) Draw a graph showing variation of photocurrent with the anode potential of a photocell.
solutions
(a) Write two main observations of photoelectric effect experiment which could only be explained by Einstein’s photoelectric equation.
(b) Draw a graph showing variation of photocurrent with the anode potential of a photocell.
solutions
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