A certain shade of blue has a frequency of 7.24 * 1014 Hz. What is the energy of exactly one photon of this light?

The energy of the photon is proportional to frequency of the photon. The constant of proportionality here is called Planck's constant with a value of 6.62607004 * 10-34 m2 kg / s. In this case, substituting to the formula E = h v where h is the constant and v is the frequency, the answer is 4.80 * 10^-19 Joules

E = hf

E = 6.63 * 10 ⁻³⁴ * 7.24 * 10¹⁴

E = 4.80012 * 10⁻¹⁹ J