The ratio of the area covered by the second orbital to the first orbital is

In Bohr's model of an atom,when an electron jumps from $n = 1$ to $n = 3$,how much energy is absorbed?

Explain the following according to Bohr's model of hydrogen:
$(i)$ Principal quantum number
$(ii)$ Radius of stationary orbit $(r)$
$(iii)$ Energy of stationary state
$(iv)$ Isoelectronic ion of $H$
$(v)$ Velocity of electron

In the Bohr series of lines of the hydrogen spectrum,the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen?

According to Bohr's model,the energy of an electron is given by $E = -\frac{2.176 \times 10^{-18}}{n^2} \, J \, atom^{-1}$. Calculate the minimum energy required to remove an electron from the $3^{rd}$ orbit of a $He^{+}$ ion,and also calculate the corresponding wavelength of the photon.

The energy required to dislodge an electron from an excited isolated $H^-$ ion,given that the ionization energy of a ground state $H$ atom is $IE_1 = 13.6 \ eV$,is: