What atomic number of an element "X" would have to become so that the 4th orbit around X would fit inside the I Bohr orbit of H atom ?

What atomic number of an element "X" would have to become so that the 4th orbit around one electron species of X ion would fit inside the first Bohr orbit H-atom?

The orbit having Bohr radius equal to 1st Bohr orbit of H-atom is :

The orbit having Bohr radius equal to 1st Bohr orbit of H-atom is :

" What is the velocity of electron in "6" th "Bohr's" orbit of "H-" atom? "

The energy of electron in the n^(th) Bohr orbit of H-atom is

What is the orbital acceleration of the electron in the first bohr orbit of hydrogen atom ?

Obtain an expression for the radius of Bohr orbit for H atom.

Obtain an expression for the radius of Bohr orbit for H-atom.