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

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:

The velocity of an electron in the first Bohr orbit of $He^+$ ion is .......

The magnetic moment of an electron due to its orbital motion is proportional to $(n =$ principal quantum number$)$

Suppose an electron in an atom experiences an attractive force towards the nucleus given by $F = k/r$,where $k$ is a constant and $r$ is the distance of the electron from the nucleus. Applying the Bohr model to this system,the radius of the $n^{th}$ orbit $r_n$ and the kinetic energy of the electron in that orbit $K_n$ are found. Which of the following relationships is correct?

The following parameter is the same for all hydrogen-like atoms and ions in their ground state.