Final answer:
The possessive adjective in the sentence 'His hat is newer than hers' is 'His'.
Step-by-step explanation:
The possessive adjective in the sentence 'His hat is newer than hers' is His. A possessive adjective is used to show ownership or possession. In this sentence, 'His' is used to show that the hat belongs to the person being referred to as 'his'.
Learn more about Possessive Adjectives