Acertain shade of blue has a frequency of 7.31 × 1014 hz. what is the energy of exactly one photon of this light?

Photon energy is the energy carried by a single photon with a certain wavelength and frequency. These terms are related by an equation. 
E = hv
where h is the Planck's constant (6.626 x 10-34 J s), v is the frequency.

We calculate the energy as follows:

E = hv

E = 6.626 x 10-34 J s ( 7.31 × 10^14 / s ) = 4.84 x 10^-19 J

4.84 x 10⁻¹⁹ J

Explanation:

The energy of a photon is given by the Planck-Einstein equation which relates the energy E of a photon to its frequency v through the Planck constant h (6.62607 x 10⁻³⁴ J·s):

E = hv

We can now substitute the values to find the energy of one photon. Hertz (Hz) is equivalent to units of s⁻¹.

E = (6.62607 x 10⁻³⁴ J·s)(7.31 x 10¹⁴  s⁻¹) = 4.84 x 10⁻¹⁹ J