The product of linear momentum and angular momentum of an electron of the hydrogen atom is proportional to $n^{x}$,where $x$ is

Energy required for the electron excitation in $Li^{++}$ from the first to the third Bohr orbit is.....$eV$

If the radius of the first Bohr orbit is $r$, then the radius of the second Bohr orbit will be

Consider that an electron is revolving in an excited state of Hydrogen atom with velocity $\sqrt{25.6} \times 10^5 \text{ m s}^{-1}$. The radius of the orbit is $x \times 10^{-9} \text{ m}$. The value of $x$ is : [Take the mass of electron to be $9 \times 10^{-31} \text{ kg}$, charge of electron = $-1.6 \times 10^{-19} \text{ C}$ and $\frac{1}{4\pi \epsilon_0} = 9 \times 10^9 \text{ N m}^2 \text{ C}^{-2}$]

The ratio of the area of the first excited state to the ground state orbit of a hydrogen atom is:

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