Questions & Answers about Ich trage die Kette heute im Büro.
German nouns have grammatical gender. Kette is grammatically feminine, so in the basic (dictionary) form it takes the article die:
- singular: die Kette (the necklace / the chain)
- plural: die Ketten (the necklaces / the chains)
You would only see der Kette if Kette were in the dative or genitive singular (e.g. mit der Kette, wegen der Kette).
Das Kette is simply wrong, because Kette is not neuter.
In Ich trage die Kette heute im Büro, die Kette is in the accusative case.
Reason: die Kette is the direct object – it is the thing being worn/carried.
- Ich = subject (nominative)
- trage = verb
- die Kette = direct object (accusative)
- heute im Büro = adverbials (time and place)
For feminine nouns, the nominative singular and accusative singular both use die, so you have to rely on the sentence role (subject vs. object) to know the case.