If the radius of a hydrogen atom in its first orbit is $a_{0}$,then its radius in the third excited state is . . . . . . . (in $a_{0}$)

If the de-Broglie wavelength of an electron in the first Bohr orbit is $\lambda$,then the minimum radial distance between the electrons in the first and second Bohr orbits is:

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

$A$ $\mu$-meson of charge '$e$',mass $208 m_e$ moves in a circular orbit around a heavy nucleus having charge $+3e$. The quantum state '$n$' for which the radius of the orbit is the same as that of the first Bohr orbit for a hydrogen atom is [approximately]:

If one were to apply the Bohr model to a particle of mass $m$ and charge $q$ moving in a plane under the influence of a magnetic field $B$,the energy of the charged particle in the $n^{th}$ level will be

To which of the following is the angular velocity of the electron in the $n$-th Bohr orbit proportional?