Energy of a photon of light of frequency v is given by hv and that having wavelength λ is hc/λ,
(i) Energy of photon of light having the frequency of 3 x 1015 Hz
= hv = 6.626 x 10-34 Js x 3 x 1015 s-1
= 1.988 10-18 J
(ii) Energy of photon of light having wavelength of 0.5 Å
= hc/λ = {6.626 x 10-34 Js x 3 x 108 ms-1}/{0.5 x 10-10 m}
= 3.98 x 10-15 J