Learn German: Packt der Händler das Porzellan denn ein? - Is the dealer wrapping the porcelain, then?

While denn is a conjunction meaning "because" when it connects two clauses, here it acts as a modal particle. Tucked inside a question, it adds flavor rather than literal meaning. It shows curiosity or surprise, making the question sound more engaged and conversational, much like adding "then" in English ("Is he wrapping it, then?").

Why is the word ein hanging at the very end of the question?

That's the separable prefix of the verb einpacken (to pack up or wrap). In a yes/no question like this, the conjugated part of the verb (packt) takes the first position, and the separable prefix gets kicked to the very end of the sentence.

Could I put denn earlier in the sentence?

Yes, modal particles are somewhat flexible. You could also naturally ask, Packt der Händler denn das Porzellan ein? Both versions are correct. Placing denn later in the sentence, as in our example, just puts a tiny bit more emphasis on the porcelain itself.

Is das Porzellan in the accusative case here?

Exactly! der Händler is the subject performing the action (nominative), and das Porzellan is the object receiving the action (accusative). Because Porzellan is a neuter noun, its article (das) looks exactly the same in both the nominative and accusative cases.