modal particle, pronoun, verb · where (interrogative pronoun used to ask for a location)

你要去哪？

pronoun, modal particle, measure word · an interrogative pronoun used to ask for a specific person or thing among a group

你想买哪本书？

pronoun, modal particle · which? (interrogative, followed by a classifier or numeral-classifier)

哪本书是你的？

pronoun · used in rhetorical questions to express negation or to mean "how could"

我哪知道他今天不来？

noun, modal particle · emphatic sentence-final particle used instead of 啊 a after a word ending in "n"

那个小朋友长得真好看哪，笑起来还有个酒窝。

proper name · specifically used in the name of the mythological deity 哪吒 Né​zhā

小时候，我最喜欢听哪吒闹海的故事。