The diagram below represents the bright-line spectra of four elements and a bright-line spectrum produced by a mixture of three of these elements.
can someone me with this one? i dont understand that at all : (

If wavelength of an element isn't marked on wavelength of mixture, it means that this element isn't part of it.
I also attached picture to make it more clear
I hope you will understand it, and oh btw the answer is element X (answer number 3)

Alpha particles have positive charge, beta particles have negative charge, and answer 4 just doesn’t make sense. thus, you are left with only one possible answer.