Learn Croatian: Ispraznio sam cijeli ormar, što mi je donijelo veliko olakšanje. - I emptied the entire wardrobe, which brought me great relief.

In Croatian, when 'which' refers to an entire preceding clause or action (in this case, the act of emptying the wardrobe), you must use što. If you were referring back to a specific noun, like the wardrobe itself, you would use koji.

Why is the verb form donijelo in the neuter gender?

It matches the relative pronoun što. When što stands in for a whole idea or action rather than a specific noun, it is treated grammatically as neuter singular. That is why the past tense verb is je donijelo (it brought).

Why does cijeli ormar look like it is in the nominative case if it is the object of the sentence?

Cijeli ormar is the direct object here, which means it is in the accusative case. However, because ormar is an inanimate masculine noun (a thing, not a living being), its accusative form is exactly the same as its nominative form.

Why are the small words mi je placed exactly where they are?

The second clause starts with što, making the space right after it the strict second position where clitics (small unstressed words) must go. When stacking clitics, the dative pronoun (mi) always comes before the auxiliary verb (je).