Question

Q1. That pen is mine is a correct determiner?​

Answer 1

The basic pronominal possessive determiners in Modern English are my, your, his, her, its, our, their and whose (as in Whose coat is this? and the man whose car was stolen). As noted above, they indicate definiteness, like the definite article the. Archaic forms include thy and mine/thine (for my/thy before a vowel).