‘Eighth’ can be an adjective, when used as an ordinal number, or a noun when used as a fraction:

This is the eighth day of my holidays (adjective describing ‘day’).

My share is one eighth of yours (noun).

‘Which’ can be an adjective or a pronoun.

Which book would you like? (adjective describing ‘book’).

Which would you like? (pronoun).

‘Other’ is an adjective.

Other people speak more quietly. (Describes ‘people’.)

‘Indeed’ is an adverb.

Have you any idea how to do this?

Indeed I have. (modifies verb ‘have’.)

‘One’ used as a number can be an adjective.

I have one hour to spare. (Quantifies ‘hour’).

It can be used also as a pronoun:

One does not do that. (impersonal form of ‘You’).

‘Apparent’ is an adjective.

There is an apparent lack of facilities. (Qualifies noun ‘lack’).