A doubly ionized lithium atom is hydrogen-like with atomic number $3.$ Find the wavelength of the radiation required to excite the electron in $L{i}^{+}$ from the first to third Bohr orbit. The ionization energy of the hydrogen atom is $13.6eV.$

A doubly ionised lithium atom is hydrogen-like with atomic number $3$. How many spectral lines are observed in the emission spectrum of the above exciting system?

A particle of charge equal to that of an electron $-\mathrm{e}$ and mass $208$ times the mass of an electron (called mu -meson) moves in a circular orbit around a nucleus of charge $+3\mathrm{e}$ (Take the mass of nucleus to be infinite). Assuming that the Bohr model is applicable to this system,
Derive an expression for the radius of the n-th Bohr orbit.

A particle of charge equal to that of an electron $-\mathrm{e}$ and mass $208$ times the mass of an electron (called mu -meson) moves in a circular orbit around a nucleus of charge $+3\mathrm{e}$ (Take the mass of nucleus to be infinite). Assuming that the Bohr model is applicable to this system. Find the value of $\mathrm{n}$ for which the radius of the orbit is approximately the same as that of the first Bohr orbit for the hydrogen atom.

A particle of charge equal to that of an electron $-\mathrm{e}$ and mass $208$ times the mass of an electron (called mu -meson) moves in a circular orbit around a nucleus of charge $+3\mathrm{e}$ (Take the mass of nucleus to be infinite). Assuming that the Bohr model is applicable to this system, Find the wavelength of the radiation emitted when the mu-meson jumps from the third orbit to the first orbit.

A hydrogen-like atom (described by the Bohr model) is observed to emit six wavelengths, originating from all possible transitions between a group of levels. These levels have energies $-0.85\mathrm{eV}$ and $-0.544\mathrm{eV}$ (including both these values) 

Find the atomic number of the atom.