According to the Bohr model for the hydrogen atom,the radius of stationary orbits is proportional to which of the following?

If the electron jumps from $7.00 \ eV$ energy level to $5.0 \ eV$ energy level,it :

Consider the following spectral lines for atomic hydrogen:
$A$. First line of Paschen series
$B$. Second line of Balmer series
$C$. Third line of Paschen series
$D$. Fourth line of Bracket series
The correct arrangement of the above lines in ascending order of energy is:

The ionization energy of a hydrogen atom is $-13.6 \ eV$. The energy required to excite an electron from the ground state to the first excited state is ...... (Avogadro number = $6.022 \times 10^{23}$)

Calculate the energy associated with the third orbit of $He^{+}$.

Energy of an electron is given by $E = -2.178 \times 10^{-18} \ J \left( \frac{Z^2}{n^2} \right)$. Wavelength of light required to excite an electron in a hydrogen atom from level $n = 1$ to $n = 2$ will be: