De or het zoopje?

The correct Dutch article is:

het zoopje

Rule Diminutives (-je, -tje, -pje): always het. See the rule
Meaning (Dutch) drankje

How to use zoopje

the zoopjehet zoopje
this zoopjedit zoopje
that zoopjedat zoopje
our zoopjeons zoopje
your zoopjejouw zoopje
every zoopjeelk zoopje
which zoopje?welk zoopje?
a big zoopje / the big zoopjeeen groot zoopje, het grote zoopje

Meaning, plural, diminutive, pronunciation and translations: WikiWoordenboek (Dutch Wiktionary) (CC BY-SA 4.0). Example sentences: Tatoeba (CC BY 2.0 FR).