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

An electron of a stationary hydrogen atom transits from the fourth energy level to the ground level. The velocity of the hydrogen atom acquired as a result of photon emission will be:
{ $R =$ Rydberg constant,$m =$ mass of hydrogen atom }

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?

In a hydrogen atom,when an electron jumps from the second to the first orbit,the energy emitted is:

The ratio of the kinetic energies of the electrons in the third and fourth excited states of the hydrogen atom is

In the following transitions of a hydrogen atom,which one corresponds to the highest frequency of emitted radiation?