The correct statement about probability density (except at infinite distance from nucleus) is :

The difference between the radii of 3^rd and 4^th
orbits of Li²⁺ is R₁ . The difference between the
radii of 3^rd and 4^th orbits of He⁺ is $$\Delta $$R₂ .
Ratio $$\Delta $$R₁ : $$\Delta $$R₂ is :

The shortest wavelength of H atom in the Lyman series is $$\lambda $$₁. The longest wavelength in the Balmar series of He⁺ is :

The region in the electromagnetic spectrum where the Balmar series lines appear is :