Den nya eleven frågar läraren var hennes klassrum ligger.

Because elev is an en-word in Swedish: en elev.

When a noun is common gender (en), its definite article is den. So:

• en elev = a student
• den nya eleven = the new student

You use det only with ett-words.

Because adjectives usually take the -a ending when they are used with a definite noun.

Here the noun is definite: den ... eleven = the ... student.

So:

• en ny elev = a new student
• den nya eleven = the new student

This -a form is very common in definite noun phrases.

Because eleven is the definite form of elev.

• elev = student
• eleven = the student

Swedish often puts definiteness at the end of the noun with a suffix:

• en elev
• eleven

And when there is also a determiner like den, Swedish usually uses double definiteness:

• den nya eleven

So both den and -en are expected here.

In Swedish, fråga någon means to ask someone. No preposition is needed.

So:

• fråga läraren = ask the teacher
• fråga en vän = ask a friend

This is similar to English ask someone, not ask to someone.

Because this is an indirect question, not a direct question.

In a direct question, Swedish usually has verb-second word order:

• Var ligger hennes klassrum? = Where is her classroom?

But after a verb like frågar, the question becomes embedded, and Swedish uses normal subordinate-clause word order:

• Den nya eleven frågar läraren var hennes klassrum ligger.

So in embedded questions, the subject usually comes before the verb:

• var hennes klassrum ligger
• not var ligger hennes klassrum

Because after a possessive like min, din, hans, hennes, vår, etc., the noun normally stays in the indefinite form.

So:

• hennes klassrum = her classroom
• not hennes klassrummet

Compare:

• klassrummet = the classroom
• hennes klassrum = her classroom

In Swedish, possessives usually replace the article.

This is a very common question.

Swedish sin/sitt/sina is a reflexive possessive, but it refers to the subject of its own clause.

In the sentence:

• Den nya eleven frågar läraren [var hennes klassrum ligger].

inside the embedded clause var hennes klassrum ligger, the grammatical subject is klassrum, not den nya eleven.

Because of that, you do not use sin/sitt here to refer back to eleven. You use hennes.

A useful rule:

• Use sin/sitt/sina when it refers to the subject of the same clause
• Use hans/hennes/deras when it does not

Compare:

• Eleven hittar sitt klassrum. = The student finds her own classroom.

  • Here eleven is the subject of the same clause, so sitt works.

• Eleven frågar var hennes klassrum ligger.

  • Here the relevant possessive is inside a subordinate clause, so hennes is used.

Also, klassrum is an ett-word, so if reflexive were possible, the form would be sitt, not sin.

Because klassrum is an ett-word.

The reflexive possessive changes form depending on the noun:

• sin
  • en-word
• sitt
  • ett-word
• sina
  • plural

So:

• sin bok = his/her own book
• sitt klassrum = his/her own classroom
• sina böcker = his/her own books

Since klassrum is ett klassrum, the matching reflexive form would be sitt.

Swedish often uses position verbs where English simply uses is.

Ligga can be used for the location of rooms, buildings, places, or things that are situated somewhere.

So:

• Var ligger skolan? = Where is the school?
• Klassrummet ligger på andra våningen. = The classroom is on the second floor.

English uses is, but Swedish often prefers ligger for physical location.

Yes. In this sentence, var means where.

• Var ligger klassrummet? = Where is the classroom?
• Hon frågar var klassrummet ligger. = She asks where the classroom is.

Just remember that Swedish var is only the word for where. It is not related to English was/were.

Because att is not used before an embedded question introduced by a question word like var, vad, när, hur, etc.

So you say:

• Hon frågar var klassrummet ligger.
• not Hon frågar att var klassrummet ligger.

Att is used with many other subordinate clauses, but not with this kind of indirect question.

Läraren is the object of frågar.

The structure is:

• Den nya eleven = subject
• frågar = verb
• läraren = object
• var hennes klassrum ligger = embedded question / content of what she asks

So the sentence means that the new student asks the teacher the question of where her classroom is.

With hennes, it means the classroom belongs to some female person, and the exact reference depends on context.

In real life, the most likely meaning is that it refers to the new student’s classroom, but grammatically hennes could in principle refer to another female person already understood from context.

That ambiguity is one reason learners often ask about sin/sitt. Swedish handles reflexive possession differently from English, and in sentences with subordinate clauses, things can become less direct.

In everyday context, people would usually understand who hennes refers to from the situation.