How many kj/mol (of photons) of energy is contained in light with a wavelength of 4966.36nm?

We know, E = Planck's constant * speed of light  / wavelength

Here, h = 6.62607004 × 10-34 m2 kg / s
c = 3 * 10^8 m/s
w = 4966.36 nm = 4966.36 * 10^-9m = 4.96636 * 10^-6 m

Substitute their values, 
E = (6.62607004 × 10-34) (3 * 10^8) / (4.96636 * 10^-6)
E = 19.88 × 10^-26 / 4.96636 * 10^-6
E = 4 × 10^-20 J
E = 4 × 10^-20 / 10^3
E = 4 × 10^-23 KJ

In short, Your Answer would be: 4 × 10^-23 KJ

Hope this helps!