In a hydrogen atom,if $V_n$ and $V_p$ are the orbital velocities in the $n^{\text{th}}$ and $p^{\text{th}}$ orbits respectively,then the ratio $V_p : V_n$ is:

Radius of the first orbit of the electron in a hydrogen atom is $0.53 \; \mathring{A}$. So,the radius of the third orbit will be ........... $\mathring{A}$.

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

The force acting on the electron in a hydrogen atom (Bohr's theory) is related to the principal quantum number $n$ as:

The radius of the first orbit of hydrogen is $r_{H}$,and the energy in the ground state is $-13.6 \text{ eV}$. Considering a $\mu^{-}$-particle with a mass $207 m_e$ revolving around a proton as in a hydrogen atom,the energy and radius of the proton and $\mu^{-}$-combination respectively in the first orbit are (assume the nucleus to be stationary):

An atom of hydrogen gas is in an excited state $n_2$. It absorbs a photon of some energy and jumps to a higher energy state $n_1$. Then,it returns to the ground state after emitting six different wavelengths in the emission spectrum. Determine the values of $n_1$ and $n_2$.