A line of wavelength [tex]\lambda[/tex] = 1091nm is observed in the hydrogen spectrum. Identify the transition that leads to this line.
I don't know what this is asking...
1/[tex]\lambda[/tex] = R(1/nf2-1/ni2)?The lines in the hydrogen spectrum are caused by an electron jumping from one of the orbits n=1,2,3,4,... to a lower one. You should be able to find a formula for the wavelength (or energy) of such a transition in terms of those two numbers). Now try putting in values for those numbers until you find a pair that approximately matches 1091nm.