Is Kollaps der, die or das?

The correct German article for Kollaps is der. The noun Kollaps is Masculine. So you always say: der Kollaps. Learn the article together with the noun — German nouns don't follow predictable gender rules most of the time.

The plural of Kollaps is: die Kollapse. In the plural, every German noun takes the article "die". So: die Kollapse. Example: ein Kollaps → zwei Kollapse.

Correct: die Kollapse. The form "die Kollapss" is wrong. The plural of der Kollaps is die Kollapse. In the nominative plural, you always use the article "die".

der Kollaps follows the four German cases. Nominative: der Kollaps, Accusative: den Kollaps, Dative: dem Kollaps, Genitive: des Kollapses. In plural: die Kollapse / den Kollapsen. Learn these forms together with the noun.

The genitive singular of der Kollaps is: des Kollapses. The genitive plural is der Kollapse. German uses the genitive to express possession or belonging. Example: die Farbe des Kollapses.

The dative plural of Kollaps is: den Kollapsen. In German, dative plural nouns usually end in "-n". So you say: "mit den Kollapsen". Use this case after prepositions like mit, von, bei, zu.

Kollaps is a noun and must be capitalized in German. You'll find example sentences above for each case. The article der stays the same in nominative singular but changes in other cases. Practice declension in your own sentences.

Yes, Kollaps is a noun (also called a substantive). German nouns are always capitalized. The article for Kollaps is der. Every German noun has a fixed article you must memorize.