Answer
(a) S={0,1,2,3,....}
(b) A={675,676,...,700}
(c) B={450,451,...500}
(d) A∩B=φ
(e) A∪B={450,451,..,500,675,676,...700}
Work Step by Step
(a) S={0,1,2,3,....}
because the wavelengths of light take a non negative integer and measured by the nearest nanometer
(b) A={675,676,...,700}
(c) B={450,451,...500}
(d) A∩B=φ, the empty set
(e) A∪B={450,451,..,500,675,676,...700}