Answer:
3.46
⋅
10
−
19
J
Explanation:
The energy of a photon is proportional to its frequency,
I hope this helps in some way. I forgot to mention that the question states they want to find THE NUMBER OF MOLES for H2O. Yherefore, you would want mol of H2O on top.
Get an equal amount of each element by adding coefficients to the different compounds.