What is the ratio of speed of electron present in second orbit of H atom and fourth orbit of `He^(+)` ?

Ratio of time period of electron in first and second orbit of H-atom would be -

What is the ratio of the speeds of an electron in the first and second orbits of a hydrogen atom?

The speed of the electron in the second orbit in a H-atom is

What is the frequency of revolution of electron present in 2nd Bohr's orbit of H- atom ?

What is the ratio of time periods (T_(1)//T_(2)) in second orbit of hydrogen atom to third orbit of He^(+) ion?

Energy of electron in a orbit of H -atom is

The angular speed of electron in the nth orbit of hydrogen atom is