Answer
See the answer below.
Work Step by Step
a) Since $c=\lambda\times\nu$ and $E=h\times\nu$, green light has a higher energy per photon because it has a smaller wavelength.
b) Red light has a wavelength close to the maximum in the visible spectrum (700 nm), so it's the 680 nm one and the green light is the 500 nm one.
c) The green light has a higher frequency because it has a smaller wavelength.
