A) A 100-watt lightbulb radiates energy at a rate of 100 J/s. (The watt, a unit of power, or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 520 nm, how many photons are emitted per second? (Assume three significant figures in this calculation.)
Express your answer using three significant figures.

B) How much energy (in \({\rm J}\)) is contained in 1.00 mole of 490\({\rm nm}\) photons?
Express your answer to three significant figures and include the appropriate units.

C) What is the de Broglie wavelength of an electron traveling at 1.48