Helmer: Rank led me to expect a splendid transformation.

Rank: [in the doorway] I understood so, but evidently I was mistaken.

Nora: Yes, nobody is to have the chance of admiring me in my dress until tomorrow.

Helmer: But, my dear Nora, you look so worn out. Have you been practising too much?

Nora: No, I have not practised at all.

Helmer: But you will need to—

Nora: Yes, indeed I shall, Torvald. But I can't get on a bit without you to help me; I have absolutely forgotten the whole thing.

Helmer: Oh, we will soon work it up again.

Nora: Yes, help me, Torvald. Promise that you will! I am so nervous about it—all the people—. You must give yourself up to me entirely this evening. Not the tiniest bit of business—you mustn't even take a pen in your hand. Will you promise, Torvald dear?

Helmer: I promise. This evening I will be wholly and absolutely at your service, you helpless little mortal. Ah, by the way, first of all I will just— [Goes towards the hall door.]

Nora: What are you going to do there?

Helmer: Only see if any letters have come.

Nora: No, no! don't do that, Torvald!

Helmer: Why not?

Nora: Torvald, please don't. There is nothing there.

How does Ibsen use dramatic irony to create suspense in this passage?

Rank says that he thought Nora would be dressed up, while Helmer says that he did not expect her to be.
Nora tells Helmer that there are no letters in the box, while the audience knows that there is a letter from Krogstad.
Nora says that no one can see her in her costume until the party, where she will dance the tarantella.
Helmer and Rank promise to help Nora practice dancing, because she has not been practicing all day.