Tranh sơn dầu ở trong bộ sưu tập.

Tranh sơn dầu means oil painting.

Breakdown:

• tranh = painting, picture
• sơn dầu = oil paint / oil-based paint

Together, tranh sơn dầu is the normal Vietnamese way to say oil painting.

One small note: tranh can sometimes feel a little general, so if you want to clearly emphasize a painting, Vietnamese often uses:

• bức tranh sơn dầu = an oil painting

In your sentence, leaving out bức is still possible, especially in short or simple examples.

Vietnamese often does not use a direct equivalent of the English verb to be in sentences about location.

So:

• Tranh sơn dầu ở trong bộ sưu tập. literally works like:
• Oil painting at/in collection.

In natural English, we translate it as:

• The oil painting is in the collection.

This is very common in Vietnamese:

• Sách ở trên bàn. = The book is on the table.
• Tôi ở nhà. = I am at home.

So the idea of is is understood from the structure.

Yes, both are related to location, but they do slightly different jobs.

• ở marks location in a general way: to be at / located at
• trong means inside / in

So:

• ở trong = to be inside

In this sentence:

• Tranh sơn dầu ở trong bộ sưu tập. means the painting is inside / in the collection.

You may also hear:

• Tranh sơn dầu trong bộ sưu tập.

This can also be understood, especially in some contexts, but ở trong makes the location relationship clearer.

Bộ sưu tập means collection.

Breakdown:

• sưu tập = to collect / collection
• bộ = set, group, collection-like unit

In this phrase, bộ helps form the noun collection in a natural way. So bộ sưu tập is the standard expression for a collection.

Examples:

• bộ sưu tập tranh = a painting collection
• bộ sưu tập tem = a stamp collection
• bộ sưu tập thời trang = a fashion collection

So in your sentence, trong bộ sưu tập means in the collection.

Vietnamese nouns usually do not show definiteness or number as clearly as English does.

So tranh sơn dầu could mean:

• the oil painting
• an oil painting
• oil paintings

Which meaning is intended depends on context.

In a simple learning sentence, English often chooses:

• The oil painting is in the collection.

But without more context, Vietnamese itself does not force that interpretation.

If you wanted to be more specific, you could say:

• bức tranh sơn dầu này = this oil painting
• một bức tranh sơn dầu = an oil painting
• những bức tranh sơn dầu = oil paintings

Often, yes.

• tranh sơn dầu = oil painting / oil paintings
• bức tranh sơn dầu = an oil painting / the oil painting

Bức is a classifier often used for pictures, paintings, and similar flat visual objects. Adding it can make the phrase sound more complete when talking about one specific painting.

So:

• Bức tranh sơn dầu ở trong bộ sưu tập. may sound more natural if you mean The oil painting is in the collection.

But the shorter version without bức is still understandable and is common in vocabulary-style or simple example sentences.

It can be either, depending on context.

It may mean:

• the painting is physically located in the collection
• the painting belongs to the collection
• the painting is included as part of the collection

With bộ sưu tập, Vietnamese can use location wording in a way that overlaps with English ideas like:

• is in the collection
• is part of the collection
• belongs to the collection

So the phrase may describe actual location, membership, or inclusion.

Sometimes yes, but the nuance changes a little.

Compare:

• Tranh sơn dầu ở trong bộ sưu tập.
  = The oil painting is in the collection.
  This clearly states location.

• Tranh sơn dầu trong bộ sưu tập...
  = the oil painting in the collection... / oil paintings in the collection...
  This can sound more like a noun phrase depending on context.

So ở helps make it clearly into a full sentence about where something is.

Without ở, the phrase may still work in some contexts, but it can feel less explicit.

A rough pronunciation guide:

• Tranh ≈ chanh with a tr sound
• sơn ≈ suhn (with the ơ vowel, which is not exactly English)
• dầu ≈ zow in northern Vietnamese, closer to yow in southern Vietnamese
• ở ≈ a short vowel somewhat like uh, with a broken rising tone
• trong ≈ chawng / chrong depending on accent
• bộ ≈ boh, with a heavy falling tone
• sưu tập ≈ suu tup

A more useful learner tip is the rhythm:

• Tranh sơn dầu | ở trong | bộ sưu tập.

If you are studying tones, the most important thing is to learn the words individually from audio, because English spelling approximations are very limited.

It is understandable, but it can feel a little bare or textbook-like because Vietnamese often includes more context.

More natural possibilities might be:

• Bức tranh sơn dầu này ở trong bộ sưu tập.
  = This oil painting is in the collection.

• Bức tranh sơn dầu thuộc bộ sưu tập này.
  = This oil painting belongs to this collection.

• Trong bộ sưu tập có một bức tranh sơn dầu.
  = There is an oil painting in the collection.

Your original sentence is grammatically understandable, but in real conversation Vietnamese speakers often add:

• a classifier like bức
• a demonstrative like này/đó
• or a different structure depending on what they want to emphasize

Yes, but the meaning shifts.

• ở trong bộ sưu tập = is in the collection
• thuộc bộ sưu tập = belongs to the collection / is part of the collection

So:

• Bức tranh sơn dầu ở trong bộ sưu tập.
  focuses on location or inclusion

• Bức tranh sơn dầu thuộc bộ sưu tập.
  focuses more on membership or ownership relationship

If you want to say the painting is one item in the collection, thuộc is often a very natural choice.