1. Beatrice: "I would eat his heart in the marketplace." (Act 1, Scene 1)
Beatrice's statement here is sarcastic because she is not literally going to eat Benedick's heart. She is simply expressing her strong dislike for him in a humorous way.
2. Benedick: "I do spy some marks of love in you." (Act 2, Scene 3)
Benedick's statement here is sarcastic because he does not actually believe that Beatrice is in love with him. He is simply teasing her and trying to get a rise out of her.
3. Claudio: "She's but a woman, and I am a man." (Act 4, Scene 1)
Claudio's statement here is sarcastic because he is trying to downplay the importance of Hero's reputation. He is essentially saying that Hero is just a woman and therefore her honor is not as important as his own.
4. Don Pedro: "The lady is dead." (Act 5, Scene 1)
Don Pedro's statement here is sarcastic because he knows that Hero is not actually dead. He is simply trying to deceive Claudio and make him think that Hero has been unfaithful to him.
These are just a few examples of the many instances of sarcasm in Much Ado About Nothing. Sarcasm is a common literary device that is used to create humor and to express characters' feelings indirectly.