Определенный или неопределённый артикль и почему? 1. I always have the/a/(-) radio on in the car for the

Question

Английский язык: Определенный или неопределённый артикль и почему? 1. I always have the/a/(-) radio on in the car for the traffic alerts. 2. approximately one third of Greece/the Greek/the Greece’s population lives in Athens.