"The soap is in the bathroom."
Translation:Το σαπούνι είναι στο μπάνιο.
When στην is followed by a word that begins with κ,π,τ,ψ,ξ,γκ,μπ,ντ or a vowel it keeps the -ν. Otherwise it is ommited.This rule also applies to την, αυτήν and the negatives δεν, μην, but not to στον/τον/αυτόν. (though you will come upon some sentences in the cource that ommit the -ν from στον/τον/αυτόν, it is wrong.)
Yes, that might be the first thing on the table when it's review time.
Yes, and also before vowels. I edited my previous message to be more complete :)
Couldn't this also be "μέσα στο μπάνιο"? When the English is "in" the Greek is often "μέσα στο" more than I would think, but not here.
You are right, it could also be like this. But in daily speech we don't say it so often (μέσα στο μπάνιο, μέσα στο δωμάτιο,...), cause "μέσα" is usually said for describing smaller spaces (e.g. μέσα στο ντουλάπι = inside the closet, and even here it's not necessary to use "μέσα")