1. He is the top of the class.

Question

2. He is at the top of the class.

3. He is the bottom of the class.
4. He is at the bottom of the class.

(Is each pair interchangable and grammatical? Is #1 or #2 opposite of #3 or #4?)

Answer 1

Numbers 2 and 4 are best.

Yes. 1 and 2 are the opposite of 3 and 4.