Breakdown of Beiðninni var svarað í þjónustuverinu.
vera
to be
í
in / into / to (before the hour, in telling time) / per (in frequency expressions)
svara
to answer
beiðnin
the request
Questions & Answers about Beiðninni var svarað í þjónustuverinu.
Why is Beiðninni in the dative case here instead of the nominative?
This is an example of the oblique passive. The verb svara (to answer) requires its object to be in the dative case. When we change an active sentence into a passive one, the object moves to the front to act as the subject, but it stubbornly keeps its dative case. So, the nominative beiðnin becomes the dative beiðninni.
Since beiðninni is a feminine noun, why is the past participle svarað in the neuter form?
In Icelandic, the past participle only agrees with the subject (changing to feminine, masculine, or plural) if that subject is in the nominative case. When the subject is in an oblique case (like the dative, as we see here), the past participle always defaults to the neuter singular form, which is svarað.
What is the base form of Beiðninni without the definite article?
The base word is beiðni (request). It is a feminine noun ending in -i, which means it actually stays as beiðni across all four cases in the singular indefinite! You only see the dative case here because of the attached definite article, which changes from -n in the nominative (beiðnin) to -nni in the dative (beiðninni).
Why does þjónustuverinu take the dative case?