Whose- Form and Function

It's a relative pronoun. It stands for 'whose $100'.

Persian LearnerWhat's the form and function of the underlined part?

It's an interrogative determiner, but the associated noun ($100) is omitted. Some grammarians call this a case of promoting the determiner to a pronoun. The complement of "wonder" is usually, as here, an indirect question. The corresponding direct question is "Whose $100 was it?"

C

What is its function if we accept it as an interrogative pronoun? Is it the subject complement?

Persian LearnerWhat is its function if we accept it as an interrogative pronoun?

(possessive) determiner (It's possible that in the textbook you are using they call it a possessive adjective.)

Consider what the answer to the direct question would be.

It was his $100. / It was my $100. / I

How if we answer the question this way?

It was his. It was mine. It was Fran's.

Persian LearnerHow about if we answer the question this way?

possessive pronoun

Ah. I see what you mean. You can call it an interrogative pronoun in the original sentence as well. In this case you can't tell the difference. It's the same word "whose" whether you have a noun after it or not.

Whose is

Now, would you please check my analysis of the whole sentence?

There was $100 on the table and Tara wondered whose it was.

There- Form: pronoun Function: dummy subject

was- Form: simple past singular verb Function: copular

$100- Form: noun phrase Function: real subject

on the table- Form: prepositional phrase Function: adverb of place

Th

Persian Learnerwould you please check my analysis of the whole sentence?

It looks really good. I think you've said everything that can be said about that sentence!