Quantum Question and Binding Energy Question

[vg19]

Hi,

I have the following MC question and I do not understand it at all. Can you please help me with this.

Determine which H atom transition (ninitial,nfinal) was responsible for the emission of a photon with a frequency of 6.17 x 1014 Hz.
[RH = 2.18 x 10-18 J; h = 6.63 x 10-34 J s ]

a. (2,3)
b. (2,4)
c. (5,2)
d. (4,2)
e. (3,2)


Also, I am stuck with this question:
A metal has a threshold wavelength, for the onset of the photoelectric effect, of 524 nm. What is the binding energy (in kJ/mol) of an electron to the metal surface?


Any help would be much appricieated
Thanks

 

[inha]

http://scienceworld.wolfram.com/physics/BalmerFormula.html

That should get you started on the first part and for the second remember that E=hc/lambda.

 

[vg19]

Thanks. For the first question though, how I do isolate to solve for the two n values? I am very confused about this

 

[lightgrav]

Look, it's multiple choice! An electron transition
from n=2 to n=3 would require (absorb) Energy.
So the photon is emitted in a transition to n = 2.
Try the middle initial state; if that gives less energy
than the photon took, then the electron must have
started from higher up (ie, n=5)