EU-kontrollen er godkjent.

Because Norwegian usually puts the definite article at the end of the noun.

• en kontroll = an inspection / a check
• kontrollen = the inspection / the check

So EU-kontrollen means the EU inspection. In this sentence, we are talking about one specific inspection, not inspections in general.

Yes. It is a compound noun: EU + kontroll.

Norwegian normally writes compound nouns as one unit. When the first part is an abbreviation or initialism like EU, a hyphen is often used to make the word easier to read. So:

• EU-kontroll
• EU-kontrollen

This is very common in Norwegian spelling.

Kontroll is a masculine noun in Bokmål:

• en kontroll
• kontrollen

That is why the definite singular form ends in -en.

Because har godkjent would be active, not passive or result-based.

• Verkstedet har godkjent bilen = The garage has approved the car
• EU-kontrollen er godkjent = The inspection is approved / has been approved

In your sentence, the focus is on the status or result, not on who did the approving. That is why er + godkjent is used.

It is originally the past participle of the verb godkjenne (to approve), but in a sentence like this it functions very much like an adjective.

You can think of er godkjent as meaning is approved or has approved status.

So grammatically, it comes from a verb, but in use here it behaves like a descriptive word after er.

Because the subject is singular.

In Norwegian, adjectives and participles often agree with the noun in number. Here the noun is singular, so godkjent is correct.

Compare:

• EU-kontrollen er godkjent = singular
• Delene er godkjente = plural

So godkjente would normally be used with plural nouns.

It is close to a passive, but more specifically it is often understood as a state/result construction: er + past participle.

Compare these:

• EU-kontrollen ble godkjent = The inspection was approved
  This focuses more on the event.
• EU-kontrollen er godkjent = The inspection is approved / has been approved
  This focuses more on the current result or status.

So yes, it has a passive-like meaning, but it especially emphasizes the resulting state.

Usually, in a normal sentence about one specific inspection, EU-kontrollen is the natural choice.

Without -en, EU-kontroll sounds more general, like EU inspection as a concept, or like a heading/title. For example:

• EU-kontroll er viktig = EU inspection is important
• EU-kontrollen er godkjent = The EU inspection has been approved

So in your sentence, the definite form is the normal one.

Because EU is an abbreviation, so it stays capitalized. Kontrollen is an ordinary noun, so it is written in lowercase unless it begins the sentence.

That is standard Norwegian spelling:

• EU-kontrollen er godkjent
• not EU-Kontrollen er godkjent