In the case of an emergency where you might not have enough time to read several lines of writing, not to mention trying to find the hazard warnings when the whole bottle is probably covered in writing, it is much easier to locate and read universal hazard symbols.
The way I would explain it is quite difficult to understand, so this is what Google says. "The wavelength (or equivalently, frequency) of the photon is determined by the difference in energy between the two states. These emitted photons form the element's spectrum. The fact that only certain colors appear in an element's atomic emission spectrum means that only certain frequencies of light are emitted." I hope this helped.
Potassium ......................
All the answers are on the actual periodic table. You should never be told to remember it so I think this is a recourse you are allowed to look at whilst doing your homework lol :) all the answers are written on it hope it helps
The answer should be...99.318!