Learn Finnish: Miksi pöydällä on taikinaa? - Why is there dough on the table?

This is an existential sentence, which states that something exists somewhere (like 'there is...' in English). In Finnish, these sentences typically start with the location (pöydällä), followed by the verb in the third-person singular (on), and end with the new information, which is the subject (taikinaa).

Why is taikinaa in the partitive case here?

In existential sentences, if the subject is an uncountable 'mass noun' like dough, coffee, or snow, it takes the partitive case. The partitive form taikinaa shows that there is an unspecified amount of dough on the table, translating closely to 'some dough'.

Could I use the nominative form taikina instead of the partitive?

You could, but it would change the meaning and the sentence structure. If you said Miksi taikina on pöydällä?, you are no longer using an existential sentence. It translates to 'Why is THE dough on the table?' and refers to a specific, known batch of dough rather than just asking why there is dough there in general.

Why does the 't' in pöytä change to a 'd' in pöydällä?