Simple mixing does not always mean a chemical reaction.
Different layers means that the materials are not miscible.
Quuestion1: Does cyclohexane react with concentrated sulfuric acid?
Question 2: If no, why?
Question 3: Does cyclohexene react with concentrated sulfuric acid?
Question 4: If yes, why and what is the product?
Question 5: If any product formed, is it miscible with cyclohexene and/or concentrated sulfuric acid?