Persian
No, old is not a proper adjective. A proper adjective is an adjective derived from a proper noun, such as Swiss cheese, Bolivian pottery, Chinese silk, etc.
Egyptian is a proper adjective.
Athenian is a proper adjective for Athens.
No, Egyptian is an adjective used to describe something of or from Egypt (a proper noun). Although Egyptian is an adjective, it is still capitalized.
Persian
The correct spelling of the proper adjective is Scandinavian.
The likely term is the proper noun, an historical region, Persia (now Iran).
Persia
Those letters will spell the proper noun or proper adjective African.
The correct spelling of the proper noun or adjective is Portuguese.
That is the correct spelling of the proper adjective Virginian (from Virginia).
The correct spelling of the proper noun or adjective is Jamaican.
The proper adjective or term for people from China is Chinese.
An adjective describes a noun. You could potentially describe a person or thing as "Vietnamese".
The correct spelling of the proper adjective and demonym is Haitian (of or from Haiti).
The proper adjective for a person, thing, or characteristic is European (capitalized).