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:

$A$ hydrogen atom absorbs radiation of wavelength $975 \, \text{\AA}$ to transition from the ground state to an excited state. To which energy level will the atom transition?

Energy levels $A, B, C$ of a certain atom correspond to increasing values of energy,that is,$E_A < E_B < E_C$. If $\lambda_1, \lambda_2, \lambda_3$ are the wavelengths of radiations corresponding to the transitions $C$ to $B$,$B$ to $A$,and $C$ to $A$ respectively,as shown in the figure. Which of the following statements is correct?

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.

What is the ground state of an atom? And what is the ionization energy and excitation energy of a hydrogen atom?

As the quantum number $n$ increases,the difference in energy between consecutive energy levels