Chemistry- Electronic Transitions Urgent help

[p.ella]

the energies of light quanta increase gradually as the color of light changes. Of the following metals, which has the largest energy change: sodium, barium, calcium, strontium, lithium, potassium, and copper (ll)



I need this within half an hour



I'm guessing it has something to do within the electron configuration, like 2s and stuff, but I don't know how to do that

PLEASE HELP! IT'S URGENT!

 

[Borek]

No need for electron configuration. They all have known, distinct colors. How does the color depend on the energy?

Question is slightly ambiguous to me, as it probably refers to the flame color, not to the color of the cation itself, but it doesn't say anything about flame.