[ur-so]

Nirvana is typically classified as grunge, which is a subgenre of alternative rock. However, grunge does have some elements of hard rock. So, while Nirvana isn’t pure hard rock, they do share some similarities with the genre.

[ur-so]

Yes, in principle, any instrument can play jazz. Jazz is a musical style, not a question of the instrument itself. Though, it’s worth noting that some instruments are more commonly associated with jazz due to their historical use in the genre.