Which of the following is the energy of a possible excited state of hydrogen? $........... \ eV$

Normally,the time taken in an electronic transition is approximately:

The radius of the second Bohr orbit is $x$. The de-Broglie wavelength of an electron in the $4^{th}$ orbit is nearly

Which of the following is correct for any $H^-$-like species?

The energy of an electron in an orbit of a hydrogen-like ion with an orbit radius of $52.9 \ pm$ in $J$ is (ground state energy of an electron in a hydrogen atom is $-2.18 \times 10^{-18} \ J$).

Explain Bohr's atomic model.