Final answer:
The weight of the book that rests on top of a table is 5 N, as explicitly stated in the question.
Step-by-step explanation:
The question asks about the weight of a book that is already stated as resting on top of a table with a weight of 5 N. The answer to the question, "What is the weight of the book?" is straightforward: it is option 2) 5 N. This is because the weight of an object is a measure of the gravitational force exerted on it, and if the book is said to weigh 5 N, that is its weight irrespective of its position (whether on a shelf or on a table).