These range in size from Pohnpei, home of the capital, Palikir, with an area of 129 square miles, to Yap and Chuuk, each with 39 square miles.  
The islands are of two general types: high volcanic islands that support a large variety of plant forms and low-lying coral atolls with poorer soil.  Each of the four states has as its population centre an elevated landmass of fairly large extent. These range in size from Pohnpei, home of the capital, Palikir, with an area of 129 square miles, to Yap and Chuuk, each with 39 square miles.  For ten points, name this republic which comprises more than six hundred islands and islets in the Caroline Island archipelago.
The islands are of two general types: high volcanic islands that support a large variety of plant forms and low-lying coral atolls with poorer soil.  
Federated States of Micronesia