For an electron moving in the $n^{th}$ orbit of an $H$-atom,the angular velocity is proportional to:

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:

When a hydrogen atom is in its first excited level,its radius is .... of the Bohr radius.

According to Bohr's theory,the radius of an electron in an orbit described by principal quantum number $n$ and atomic number $Z$ is proportional to:

The ionization potential for the second $He$ electron is ...... $eV$.

$A$ muon is an unstable particle with a mass of $207 \, m_e$ and a charge of either $+e$ or $-e$. $A$ muon $(\mu^-)$ is captured by a hydrogen nucleus to form a muonic atom. If the proton captures the $\mu^-$, find the ionization energy of this atom in $keV$.