What element has a hygrogen-like specturm whose lines have wavelength four times shorter than those of atomic hydeogen?

Explanation

If all wavelength are four times shorter but otherwise similar to the hydrogen atom specturm then the energy levels of the given atom must be four times greater.
This means `E_(n)= -(4E_(H))/(n^(2))`
compared to `E_(n)= -(E_(H))/(n^(2))` for hydrogen atom. Therefore the specturm is that of `He^(+)ion(Z-2)`