60. The wavelengths satisfy mλ = 2d sin θ = 2(275 pm)(sin 45
◦
) = 389 pm. In the range of wavelengths given,
the allowed values of m are m = 3, 4, with the corresponding wavelengths being 389 pm/3 = 130 pm and389 pm/4 = 97.2 pm, respectively.