In the following sentence, is the word empty an adjective? It seems like it would be a noun/direct object

Question

The same with this sentence:
The good bike was expensive. Is expensive a noun/direct object, or an adjective?

Answer 1

You didn't post the first sentence.

In the second sentence, "expensive" is an adjective. Because it follows a "to be" verb and describes the subject, it is a predicate adjective.