The radius of the innermost electron orbit of a hydrogen atom is $5.3 \times 10^{-11} \ m$. What is the ratio of the radii of the orbits for $n=2$ and $n=3$?

$A$ $15.0\, eV$ photon collides with and ionizes a hydrogen atom. If the atom was originally in the ground state (ionization potential $= 13.6\, eV$),what is the kinetic energy of the ejected electron? .......... $eV$

The wavelengths of the spectral lines in the spectrum of deuterium $(_{1}H^{2})$ differ slightly from those in the spectrum of hydrogen $(_{1}H^{1})$ because ...

The radius of the orbit of an electron in a Hydrogen-like atom is $4.5 a_0$,where $a_0$ is the Bohr radius. Its orbital angular momentum is $\frac{3h}{2\pi}$. It is given that $h$ is Planck constant and $R$ is Rydberg constant. The possible wavelength$(s)$,when the atom de-excites,is (are) :
$(A)$ $\frac{9}{32R}$ $(B)$ $\frac{9}{16R}$ $(C)$ $\frac{9}{5R}$ $(D)$ $\frac{4}{3R}$

In the $n^{\text{th}}$ Bohr orbit,the ratio of the kinetic energy of an electron to the total energy of it is:

If an electron is revolving around the hydrogen nucleus at a distance of $0.1 \,nm$, what should be its speed?