Conturary to peoples belief the mayans were not united as one empire. true or false?

The impact of a large asteroid comet with earth has been proposed to have caused the extinction of the dinosaurs. the impact site of this comet is in or near

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

Asap will mark geography final plz ! what are the benefits of international aid? (give me the right evidence )