For a hydrogen atom,which of the following electron transitions requires the highest energy?

Photon of the maximum frequency will be absorbed in the transition (for $H$ atom):

For $Li^{2+}$,the ratio of radii $r_2 : r_5$ is:

The shortest wavelength of $H$ atom in the Lyman series is $\lambda_{1}$. The longest wavelength in the Balmer series of $He^{+}$ is:

The energy of an electron in the first Bohr orbit of $H$-atom is $-13.6 \ eV$. The possible energy value of an electron in the first excited state of $Li^{2+}$ is (in $eV$)

The values of Planck's constant and the speed of light are $6.63 \times 10^{-34} \ J \ s$ and $3.0 \times 10^8 \ m \ s^{-1}$ respectively. Find the approximate wavelength in nanometers $(nm)$ of a light ray with a frequency of $8 \times 10^{15} \ s^{-1}$.