List of top Physics Questions on Atoms asked in UP Board XII


An atom makes a transition on receiving energy from an external source, as shown in the figure. Depict the lines of possible spectrum and calculate the wavelength of any two spectral lines. (Energy levels: \(n=1\) at 0, \(n=2\) at 4.86 eV, \(n=3\) at 6.67 eV, \(n=4\) at 8.80 eV.)
Radiation of some definite frequency are either absorbed or emitted by the atoms. Explain the reason.
Enunciate the postulates of Bohr\'s model for the hydrogen atom. Show the spectral lines in the (i) emission and (ii) the absorption spectrum corresponding to the transition of hydrogen atom from \(n = 1\) to \(n = 3\) energy states.
OR
What is mass-energy conservation law? A neutron disintegrates into a proton, a \(\beta\)-particle and an antineutrino. The disintegration process is: \[ {}_{0}n^{1} \rightarrow {}_{1}H^{1} + {}_{-1}\beta^{0} + \bar{\nu} \] Find out the energy produced in this process in MeV. (Mass of neutron \(= 1.6747\times10^{-27}\) kg, Mass of proton \(= 1.6725\times10^{-27}\) kg, Mass of electron \(= 9.1\times10^{-31}\) kg.)
Energy of the \(n^{th}\) state of a hydrogen atom is \(E_n=-\dfrac{13.6}{n^2}\ \text{eV}\). A hydrogen sample is prepared in a particular excited state A. Photons of energy \(2.55\ \text{eV}\) get absorbed by the sample to take some electrons to a particular further excited state B. Find the quantum numbers of states A and B.
Energy of hydrogen atom in ground state is −13·6 eV. What will be the kinetic energy and the potential energy of the electron in the state?
The wavelength of first line of Balmer series of hydrogen atom is \( 6563\ \text{\AA} \). Determine the wavelength of second line.
OR
What do you mean by polarization of light? How are unpolarized and plane polarized lights represented? Which nature of light waves is proved by polarization?
In which region of the electromagnetic spectrum does the Lyman series of hydrogen lie?
Write the Bohr's postulates for hydrogen atom. How did Bohr remove the drawbacks of Rutherford's model of atom?
OR
Derive the formula for the electric field outside a charged hollow sphere with the help of Gauss's law.
The energy of hydrogen atom in ground state \( (n = 1) \) is \( -13.6 \) eV. To which highest energy-state the hydrogen atom can be made to reach by the photon of energy \( 12.09 \) eV?
OR
What is meant by interference? Write the conditions for constructive and destructive interference.
In Rutherford's scattering experiment, the path of a scattered \( \alpha \)-particle is:
Give the postulates of Bohr's atomic model and draw the energy level diagram for the first three lines of the Balmer series in the hydrogen atomic spectrum.
State the result obtained from Rutherford's \(\alpha\)-particle scattering.