Ich zeichne den Trödel mit Preisen aus.

Because the verb here is auszeichnen, which is a separable verb.

In a normal main clause, German often splits separable verbs:

• Ich zeichne den Trödel mit Preisen aus.

So:

• zeichne = the conjugated part
• aus = the separable prefix, sent to the end

This is very common in German:

• Ich rufe dich an. = anrufen
• Er steht früh auf. = aufstehen

The full verb is auszeichnen.

In different structures, it behaves like this:

• Infinitive: auszeichnen

  • Ich will den Trödel mit Preisen auszeichnen.

• Main clause, present tense: split

  • Ich zeichne den Trödel mit Preisen aus.

• Perfect tense: usually together in the participle

  • Ich habe den Trödel mit Preisen ausgezeichnet.

• Subordinate clause: together again

  • ..., weil ich den Trödel mit Preisen auszeichne.

So the split mainly happens in independent main clauses.

Because Trödel is the direct object of the verb, so it is in the accusative case.

The noun Trödel is masculine:

• nominative: der Trödel
• accusative: den Trödel

So:

• Der Trödel ist alt. = subject, nominative
• Ich zeichne den Trödel aus. = object, accusative

That change from der to den is a standard masculine accusative pattern in German.

It is grammatically singular, but it often works like a mass noun or collective noun.

That means Trödel can refer to:

• junk
• clutter
• old odds and ends
• second-hand stuff

So even though it is singular, it can refer to a whole pile of things, much like English stuff or junk.

That is why den Trödel can mean a collection of items, not just one object.

Because the preposition mit always takes the dative case.

Here Preise is plural, so in the dative plural it becomes Preisen:

• nominative plural: die Preise
• dative plural: mit Preisen

That extra -n is very common in dative plural when the noun does not already end in -n or -s.

So:

• mit Preisen
• mit Kindern
• mit Büchern

Also, there is no article here because it is an indefinite plural idea: with prices / with price labels.

Here it means price, not prize.

German Preis can mean either:

• price
• prize/award

But context makes the meaning clear. Since Trödel is something being labeled or sold, mit Preisen auszeichnen means marking it with prices.

So in this sentence, think:

• price labels
• price markings

not awards or prizes.

Using den Trödel suggests a specific, known batch of junk/second-hand goods.

So the speaker is probably talking about particular items:

• the junk we have here
• that second-hand stock
• the clutter being prepared for sale

If you said Trödel with no article, it would sound more general:

• Ich zeichne Trödel mit Preisen aus. = I mark second-hand goods with prices / I do that kind of work in general.

Using einen Trödel would sound odd, because Trödel is usually not treated as one single countable item. It is more like junk or stuff in English.

Yes, it is a correct and fairly standard verb, especially in retail or formal contexts.

Waren mit Preisen auszeichnen is a common expression for:

• marking goods with prices
• labeling items with prices

In more everyday speech, people might also say things like:

• mit Preisen versehen
• beschriften
• Preisschilder anbringen

But auszeichnen is absolutely normal, especially when talking about goods for sale.

Yes, the word order can change, but the finite verb still has to stay in second position in a main clause.

The neutral version is:

• Ich zeichne den Trödel mit Preisen aus.

You can move other elements for emphasis:

• Den Trödel zeichne ich mit Preisen aus.
• Mit Preisen zeichne ich den Trödel aus.

These are possible, but the original sentence is the most straightforward and neutral.

The important thing is:

• one element comes first
• the finite verb comes second
• the separable prefix aus stays at the end in a main clause