"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"
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.
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.