If an atom has $x$ energy levels,what will be the total number of spectral lines in its emission spectrum?

If the energy of a photon is $14 \, eV$ and it interacts with a hydrogen atom,which of the following is correct?

Time taken for an electron to complete one revolution in the Bohr orbit of hydrogen atom is

The emission spectrum of hydrogen is found to satisfy the expression for the energy change $\Delta E$ (in joules) such that $\Delta E = 2.18 \times 10^{-18} \left( \frac{1}{n_1^2} - \frac{1}{n_2^2} \right) \, J$ where $n_1 = 1, 2, 3 \dots$ and $n_2 = 2, 3, 4 \dots$. The spectral lines correspond to the Paschen series when:

The ratio of the time period of an electron in the first and third orbit of an $H$-atom would be:

In a hydrogen atom, an electron is transferred from an orbit of radius $1.3225 \ nm$ to another orbit of radius $0.2116 \ nm$. What is the energy (in $J$) of the emitted radiation?