"The chair is on the table."
Grammatically that makes sense, but in this instance the question is worded differently; "The chair is on the table." with the chair being the topic of the sentence. Your sentence comes closer to "On the table there is a chair." Notice how ですis used instead of あります, this indicates that the topic may already be implied to the listener. It is the difference of "it is" vs "there is"
You can't say 上にです because the particle に is followed by a verb/action, and です isn't (quite) a verb/action, it's an affirmative copula.
If you want to use に, you need to follow it with あります for example. 椅子はテーブルの上にあります The chair exists on the table. / The chair is on the table.
です／あります are difficult concepts to understand and differentiate, for English-speaking learners, because in English we always use the same word: "is". But they are different concepts in Japanese, sort of like in Portuguese you have the verbs "ser", "estar" and "haver", but in English they are translated (most of the time) to the same word: "is".
EDIT: Let me give you an example in Portuguese:
"a cadeira ESTÁ na mesa." The chair IS on the table.
"HÁ uma cadeira na mesa." There IS a chair on the table.
"ESTÁ uma cadeira na mesa." There IS a chair on the table.
I've capitalized the verbs. As you can see, they are different in Portuguese, but always the same in English.
The same happens in Japanese, so it's helpful to rely less on English translations, cause you need to internalize that です／あります are different concepts.
です goes on the end of a sentence that could be complete without it, to make it more polite and seal it. の上 is okay without です and couldn't use あります. 上に is not complete without あります and would be weird with です.
の上です is used instead of 上にあります because the latter trends more towards the object being above in general, and the former is closer to the object making up (being) the space above.
Thanks for posting this. I thought the exact same thing. If anybody could help clarify, that'd be much appreciated.
I've since learned that "noun + の上 / の下" is a perfectly valid expression in Japanese. In fact, that seems to be the way Japanese expresses the location of things. It can be understood as "the top of (noun)" or "below of (noun)". But I still don't know why に can go absent here.
From what I know, は and が are used in the same places, but still have slight differences in when they are used. There is a really good article on this here: https://www.japanesepod101.com/japanese-particles/ that helped me understand where particles go and why they're used how they are.
Thank you for your reply.
I still do not quite understand this situation. So the word "です" doesn't mean "it is" here? As far as I understood this, it supposed to be a verb here and also a predicate. But in this case, is "です" a verb in this sentence or a sort of particle? Could you elaborate more the idea of "[positive]" block? Thank you.
Well the word (not that much of a word, more of a sentence suffix) です is intranslatable, in the sense that it can be interpreted to mean "it is" or "to be" or similar, but it doesn't actually mean that. In my opinion the best way to understand です is to understand it as a positive confirmation of what the sentence is actually saying. A polar opposite (and a step more polite) would be ありません, which is the polite declination of what the sentence depicts is in fact, in negative state, or not true.
I did that too but i think its very marginally a case of the simplicity of as for the chair needs to be stressed. The the table is a bit like him or her with the の and then on top of is. Its just a bit more obvious because they are staying away from あります. I think its marginal and I am always going to look and sound like a foreigner but i want to get it right right :)
I'm no expert, but の is more for possession than location. It pertains to location in these exercises because objects, like the table, possess locations. Think of, テーブルの上, as "the table's top." The top belongs to the table. Just like 彼の名前. The name belongs to him. Now, the entire phrase, "テーブルの上" becomes a location. I actually answered this one with テーブルの上に椅子があります.
The problem is not in the に, it's in the です. です is usually translated as "is", but it's not really a verb, it's a copula - basically [noun1][subject marker][noun2][です] is like saying [noun1]=[noun2]. Here you don't have a "noun2", you just have a location, which you could omit or put in front, it's not part of the core sentence. So you can't use です, you have to use a verb such as "exists" (あります or ある in the plain form).
Because now you have shifted the topic marker pointing toward "on top", so you're essentially saying, with slightly broken grammar "on top of the table, there is a chair", which is technically not incorrect, but you'd probably want
Which still begins with "on top of the table", but now the focus is on the chair 椅子, which is on the table あります
I also doubt duolingo would accept this answer, but there is only so much an automated system can do
I will say that there are a lot of cases where です is not completely neccessary and is just there to make the sentence more formal/polite (especially if the sentence ends with an い-adjective). However, I do think it would be neccessary in this case to have です or at least だ (plain form) to make sure it's it comes across as "the chair is above the table" rather than sounding weird like "the chair is the table's above." Anyone feel free to correct me if I'm wrong though.
The noun before the の modifies the noun that comes after it
That would be "The above's table" or "The table of the above" (the table on the top, somewhat implying there are other tables under this table)
instead of テーブルの上 "the table's above / the above of the table" (on top of the table)