What is the ratio of radius of `K` orbit in `H` atom to the radius of `M`-orbit of `Li^(+2)`?

In an atom the ratio of radius of orbit of electron to the radius of nucleus is

In an atom the ratio of radius of orbit of electron to the radius of nucleus is

if a is the radius of first Bohr orbit in hydrogen atom, the radius of 3^rd orbit is

if a is the radius of first Bohr orbit in hydrogen atom, the radius of 3^rd orbit is

The ratio of radius of second orbit of hydrogen to the radius of its first orbit is :

The ratio of radius of second orbit of hydrogen to the radius of its first orbit is :

The ratio of radius of first orbit in hydrogen to the radius of first orbit in deuterium will be :

Calculate the ratio of the radius of 1^(st) orbit of H atom to that of 4^(th) orbit. Hint : r_(n) prop ( n)^(2)