The spoon is dirty. Do you ahve a clean it/one?
I'm going to buy a black it/one.
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Do we have to use only 'one' instead of 'it'? (above)
Do you like baseball?
No, I don't like one/it.
(What about this one? What do we have to use, one, or it?)
Yes, "it" is not appropriate there.
"it" is a pronoun and refers to a specific identifiable noun.
Do you like baseball?
Yes, I like it. would be correct, because we know that "it" refers to baseball.
You would not say, I am going to buy a black "it"... because you have no idea what "it" refers to.