A) c = 3 x 10^8 m/s
f = 7.15 x 10^14 Hz
c = λ x f (=) λ = 3 x 10^8 / 7.15 x 10^14 = 4.19 x 10^-7 m = 419.6 nm
B) E = h f
H = Planck's constant = 6.63 x 10^-34 J/s
E = 6.63 x 10^-34 x 7.15 x 10^14 = 4.74 x 10^-19 J
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