Atoms and Nuclei · Physics · IAT (IISER)
MCQ (Single Correct Answer)
1
Atomic masses of two oxygen isotopes ${ }_8^{16} \mathrm{O}$ and ${ }_8^{18} \mathrm{O}$ are 15.99491 u and 17.99916 u , respectively, where $u$ is the atomic mass unit. Masses of protom and neutron are given by 1.00727 u and I .00866 u , respectively. The speed of light is c . What is the difference between the binding energies of ${ }_8^{18} \mathrm{O}{ }_8^{16} \mathrm{O}$ nuclei in units of $u c^2$ ?
IAT (IISER) 2024
2
Consider the Bohr model of an atom where an electron of charge $-e$ revolves around a nucleus of charge $+e$ in an orbit of radius $r$. The electron has an orbital angular momentum $2 h$. If the nucleus had charge $+2 e$, what would have been the radius of the orbit of the electron with the same principal quantum number?
IAT (IISER) 2023
3
An electron of mass $m_e$ has a speed $u_n$ in the $n^{\text {th }}$ Bohr orbit of a hydrogen atom. The normalized speed $V_n$ is given as $V_n=u_n / c=1 / 685$ and the mass of the electron in the units of energy is given as $M_e=m_e c^2=0.51 \times 10^6 \mathrm{eV}$, where $c$ is the velocity of light in a vacuum. It is given that $\frac{e^2}{2 \epsilon_0 h c}=1 / 137$. The Planck's constant h is given as $4.13 \times 10^{-15} \mathrm{eV}-\mathrm{sec}$. The electron makes a transition from $n^{\text {th }}$ orbit to the ground state of the atom. What is the frequency of the emitted photon?
IAT (IISER) 2020