The ionisation potential of hydrogen atom is $13.6 \ V$. The energy required to remove an electron from the second orbit of hydrogen is......$eV$.

An electron of a hydrogen atom in an excited state has an energy $E_n = -0.85 \ eV$. The maximum number of allowed transitions to lower energy levels is:

$A$ stationary hydrogen atom has an electron that transitions from the fifth energy level to the ground level. The velocity that the atom acquires as a result of photon emission will be: ($m$ is the mass of the atom,$R$ is Rydberg constant,and $h$ is Planck's constant).

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.

An electron of a hydrogen-like atom,having $Z=4$,jumps from the $4^{\text{th}}$ energy state to the $2^{\text{nd}}$ energy state. The energy released in this process will be $......... \text{eV}$.
(Given $Rch = 13.6 \text{ eV}$)
Where $R =$ Rydberg constant,
$c =$ Speed of light in vacuum,
$h =$ Planck's constant.

In a hydrogen atom,if the energy difference between the $n = 2$ and $n = 3$ orbits is $E$,how much energy (in terms of $E$) is required to remove an electron from the ground state?