The ground state energy of a hydrogen atom is $-13.6 \, eV$. When its electron is in the first excited state,its excitation energy is ...... $eV$.

An electron collides elastically with an $H$-like atom and excites it from the ground state to $n = 3$. Find the energy transferred to the $H$-like atom in $eV$.

$A$ hypothetical atom has only three energy levels. The ground level has energy,$E_1 = -8 \ eV$. The two excited states have energies,$E_2 = -6 \ eV$ and $E_3 = -2 \ eV$. Which of the following wavelengths will $NOT$ be present in the emission spectrum of this atom (in $nm$)?

$A$ photon of wavelength $\lambda$ is absorbed by an electron confined to a box of length $L = \sqrt{(35 h \lambda / 8 m c)}$. As a result,the electron makes a transition from state $k=1$ to the state $n$. Subsequently,the electron transitions from the state $n$ to the state $m$ by emitting a photon of wavelength $\lambda^{\prime} = 1.75 \lambda$. Then,

In hydrogen and hydrogen-like atoms,the ratio of the difference of energies $E_{4n}-E_{2n}$ and $E_{2n}-E_{n}$ varies with its atomic number $Z$ and $n$ as:

Inner shell electrons in atoms moving from one energy level to another lower energy level produce