In the sentence:
would I use
在る or 有る?
(I know that today it's almost always written in Kana) Thanks in advance :)!
有る is for possession; 在る is for existence. Though there can be some overlap. And 或る (even though you didn't ask) is actually an adjective for "a particular/certain", like in
So in this case, I'm mostly certain it would be 有る since you "have" homework.
Here are some words that might help remember the difference:
Just a little bit of background on this:
As you mentioned, it is generally written as
ある these days. In the past, there was a clearer differentiation based on grammatical properties, i.e. that
有る was used in a transitive sense like
Xを所有する ('to possess X'), whereas
在る was used in an intransitive sense like
Xが存在する ('X exists'). However, that distinction seems to have become blurred somewhat since the Hiragana
ある became dominant.
Nonetheless, you can make an argument that if you were to use kanji to represent
ある, you could base your choice on those older usages mentioned above. In the case of your specific example, there is an implied subject to the sentence (私は is omitted but clearly understood) and an object to the sentence (宿題). This would mean that the transitive sense of 所有する would be a more appropriate choice.
Therefore the correct choice would be
有る - assuming that you are communicating the meaning 'I' the subject of the sentence, have homework today.