Czy na końcu tego zdania ma być pytajnik czy kropka?

At the beginning of a sentence, czy is a question marker. It tells you that the whole sentence is a yes/no-type question or an alternative question.

Unlike English, Polish does not usually make questions by changing word order, so czy often does that job instead.

So:

• Ma być kropka. = There should be a full stop.
• Czy ma być kropka? = Should there be a full stop?

In your sentence, czy signals from the start: this is a question.

The second czy means or in the sense of choosing between two possibilities.

So the sentence has two different uses of czy:

• the first Czy = marks the whole sentence as a question
• the second czy = or

That is why Czy ... pytajnik czy kropka? means:

Should there be a question mark or a full stop?

This is very normal in Polish.

Na końcu means at the end.

So:

• na końcu zdania = at the end of the sentence

Do not confuse it with w końcu, which often means finally, eventually, or sometimes after all.

Compare:

• Na końcu zdania jest kropka. = There is a full stop at the end of the sentence.
• W końcu zrozumiałem. = I finally understood.

So in this sentence, na końcu is the correct expression.

Because after koniec / na końcu, Polish uses the genitive for the thing whose end you mean.

The hidden pattern is:

• koniec czego? = the end of what?

So:

• koniec zdania = the end of the sentence
• na końcu tego zdania = at the end of this sentence

Here:

• zdanie is the basic form
• zdania is the genitive singular
• to changes to tego in the genitive singular

So tego zdania literally means of this sentence.

It is the locative singular of koniec.

The preposition na can take different cases, but here it expresses location, so it takes the locative:

• na końcu = at the end

So the form changes like this:

• koniec → końcu

This whole chunk, na końcu, behaves like a fixed expression meaning at the end.

Ma być literally means something like is to be or is supposed to be.

The structure mieć + infinitive often expresses:

• expectation
• instruction
• what is intended
• what is correct in a given situation

So here ma być is not just about what happens to be there right now. It asks what should be there.

Natural translations in English would be:

• Should there be ... ?
• Is there supposed to be ... ?

That is why ma być works well in a sentence about punctuation rules.

Because jest and ma być are not quite the same.

• jest = is
• ma być = should be / is supposed to be

Compare:

• Na końcu tego zdania jest kropka. = There is a full stop at the end of this sentence.
• Na końcu tego zdania ma być kropka. = There should be a full stop at the end of this sentence.

Your sentence is asking about the correct punctuation choice, not just describing what is physically there, so ma być is more natural.

They are in the nominative singular:

• pytajnik = question mark
• kropka = full stop / period

In this sentence, they are the two possible things that could be at the end of the sentence. Polish commonly leaves nouns in this basic form in structures like this with być.

So:

• ma być pytajnik
• ma być kropka

both sound natural.

Yes. Pytajnik is a normal, common word for question mark.

You may also see:

• znak zapytania = question mark

That version is a bit more explicit and literally means question sign.

So both are correct, but:

• pytajnik is shorter and very common
• znak zapytania is also standard and may sound slightly more formal or descriptive

Similarly:

• kropka = full stop / period

Yes. Polish word order is fairly flexible.

For example, you could also say:

• Czy na końcu tego zdania ma być kropka czy pytajnik?
• Na końcu tego zdania ma być pytajnik czy kropka?

These versions are still understandable. The difference is mostly about focus or emphasis, not basic meaning.

The original sentence is a natural, neutral way to ask the question.

It should end with a question mark.

Even though the sentence is talking about punctuation, it is still grammatically a direct question:

Czy ... ma być pytajnik czy kropka?

That means the whole sentence itself takes ?

So the correct written form is:

Czy na końcu tego zdania ma być pytajnik czy kropka?