I understand the declension of что -- it's inanimate/неодушевлённый, so of course it should be
Nom: что Acc: что Gen: чего Dat: чему Inst: чем Prep: чём
Likewise кто is animate/одушевлённый, so it should be
Nom: кто Acc: кoго Gen: кoго Dat: кoму Inst: кем Prep: кoм
These are basically just modified versions of the standard masculine adjective declension pattern (somewhat like the declension of "день" -- the nominative is irregular, but everything else is normal).
But if что is inanimate, then shouldn't also "ничто" be inanimate/неодушевлённый? And yet "ничто" always seems to be declined as if it were animate/одушевлённый (кто and никто don't have this consistency issue, for example).
Specifically, I have noticed that
is almost always used for the accusative form of ничто, even though I would have only expected it to be used for the genitive form.
Can someone help me?
EDIT: Here are some (probably incorrect) examples of what I am talking about:
Это не возможно делать эту задачу.
Это не возможно делать ничего.
EDIT: Here is a related question on this website which phrases the issue better than I do:
According to this website:
In "proper" Russian, the direct object of the negated verb is supposed to be put into the genitive case regardless of gender. This doesn't always happen in speech, but it is nonetheless recommended, particularly in writing.
Apparently this is also an issue in other Slavic languages: http://forum.wordreference.com/threads/all-slavic-languages-genitive-after-negated-verbs.710336/
And apparently it is also a very complicated issue in Russian, since there has been much linguistic research (apparently for even more than a century) into when and why the genitive is sometimes used for the direct objects of negated verbs, and it seems like basically there are no hard-and-fast rules and whatever rules exist are rapidly changing over time:
This feature of Russian might explain why genitive is usually listed before accusative in declension tables written in Russian, since the genitive is in some cases associated with direct objects.
When I asked my native-speaker friend about this, they gave one answer, then decided that answer was wrong, gave the opposite answer, and then admitted that they don't know.
Since the accusative is used always for direct objects in other languages, and it is used sometimes for the direct objects of negated verbs in Russian, and there is no 100% rule mandating that the genitive must be used for such direct objects, I think I am probably just going to always use the accusative for the direct object, regardless of whether the verb is negated or not, and let the chips fall where they may. It doesn't seem like there is any practical advantage to using two different cases for direct objects anyway, whereas there are many obvious disadvantages to such a system.